Herpetology , (Gr. Herpetology 0800460 , reptile or creeping thing, and Herpetology 0800461 discourse), the branch of zoology which treats of the structure and classification of reptiles. The present article will be confined to the last division, the first being more properly noticed under Reptiles. The Egyptian and other ancient authors knew well the distinctions between the four reptilian orders, generally called tortoises, lizards, serpents, and frogs; Aristotle described them as terrestrial, red-blooded animals, laying eggs, and with four or no feet, mentioning tortoises, frogs, crocodiles, lizards, and serpents, and indicating the first three as amphibians. Pliny, four centuries later, divided reptiles into terrestrial, aquatic, and aerial, but he has mostly copied Aristotle, adding a great variety of fabulous stories whose influence has extended in the popular mind even to the present time. Gesner, in the 16th century, devoted a considerable part of his writings to the natural history of this class, illustrated with wood engravings, and conveniently arranged in alphabetical order.

Aldrovandus, toward the end of the same century, wrote two books on serpents and lizards, compiling chiefly from the Greek and Arabian authors, and collected much information from the synonymy of reptiles, their symbolic history, and their uses in medicine. Ray published in London, in 1693, a synopsis of serpents, in which the manner of respiration, the size and color of the eggs, and similar characters, are made the basis of an unnatural classification. - Linnaeus divided the class of reptiles into orders, genera, and species in his Systema Naturoe; calling them, however, amphibia, and characterizing them by the three principal marks of naked or scaly body, teeth sharp and without molars, and no fins with rays; he made two orders, serpents (without limbs) and reptiles (with limbs). In his third class, as given in Gmelin's edition of 1788, the order reptiles are those breathing by lungs, with four limbs, and a simple male sexual organ; serpents, on the other hand, have a rounded body without distinct neck, moving by its undulations, with dilatable and non-consolidated jaws, and without limbs, fins, or external ears.

In the first order were four genera, the tortoise, dragon, lizard, and frog; and in the second, crotalus, boa, coluber, anguis, amphisboena, and coecilia, most of these genera being subdivided into numerous species. Lau-renti, in 1768, published a synopsis of reptiles, very remarkable for the time. Leaving tortoises out of the class, he gives their characters as follows: cold-blooded animals, without hair or mamma3, with lungs acting without diaphragm and almost without the aid of the ribs (swallowing air into them), torpid in winter, devouring their prey without chewing, and digesting it very slowly, able to exist for months without food, and renewing their youth by changing their skins. Lacepede, in 1788-'9, in a work continuing that of Buffon, entitled Histoire naturelle des quadrupedes ovipares et des serpents, divided reptiles into four classes - tailed and tailless oviparous quadrupeds, biped reptiles, and serpents; the first containing the tortoises and saurians, the second the frogs and toads, the third and fourth being sufficiently characterized by the names; he made only 292 species.

Alexandre Brongniart, in 1799, taking into consideration not only the external characters but those presented by the mode of generation and development, divided reptiles into the four orders of chelonians, saurians, ophidians, and batrachians. In 1800 Du-meril introduced into the first volume of his Lecons d' anatomie comparee a classification adopting the names of Brongniart, and separating the batrachians as a distinct order. Daudin, in 1802-'4, published a general treatise on reptiles, at the end of the eighth and last volume of which is a resume in which he divides the class into four orders, like Brongniart. Oppel, a Bavarian naturalist, published at Munich in 1811 a small quarto volume on the orders, families, and genera of reptiles, in which he adopts a mode of arrangement borrowed principally from Dumeril. Latreille, in his Histoire naturelle des reptiles (1802), followed the classification of Lacepede with some slight modifications; in 1825, in his Families du regne animal, adopting most of the divisions and some of the names of contemporary her-petologists, he makes two classes, reptiles and amphibians.

Cuvier, in his Tableau elemen-taire de l'histoire naturelle des animaux, in 1798, divided reptiles, with Lacepede, into oviparous quadrupeds, serpents, and bipeds, giving, however, some new views on their division into orders, correcting errors in generic characters, and advocating a classification founded on organization. In 1817, in his Regne animal, and in the second edition in 1829, Cuvier published a new arrangement, based on internal as well as external structure, and following chiefly the method of Dumeril, for many years professor of this branch in the museum of natural history at Paris. He makes four orders, of which the chelonians, saurians, and ophidians have a heart with two auricles, and the batrachians with a single auricle, the first two with limbs, the third without them; in the chelonians the jaws are toothless and corneous; in the saurians the jaws are furnished with teeth, and the limbs with five or four toes to each, including the crocodilians, lacer-tians, iguanians, geckotians, chameleonians, and scincoids; in the ophidians the skin is either scaly as in anguis and the true serpents, or naked as in coecilia; in the batrachians the tail may be absent or long, the feet four or two, and the lungs with or without coexistent branchiae.

De Blainville, in 1822, established two classes for reptiles (osteozoaires), reptiles proper (squammiferes ornithoides), and ichthyoid amphibians. Dr. J. E. Gray, in 1825, published a synopsis of the reptiles and amphibians of North America; in the first class he makes five orders: 1, emydo-saurians or loricata; 2, saurians; 3, saurophidians, such as the skinks and chal-cidians; 4, ophidians or serpents, divided into the venomous and non-venomous groups; and 5, chelonians. The amphibians he makes a class by themselves, placing among them all batrachians, in the four orders of anoura, uro-dela, sirens, and apoda or pseudophidians (coeci-lioe). This very natural system is founded largely on that of Oppel. In 1831 the same author published, in vol. ix. of Griffith's edition of Cuvier's "Animal Kingdom," a second synopsis with short descriptions; he divides reptiles, exclusive of amphibians, into two sections : cataphracta, or shielded reptiles, and squamata, or scaly reptiles. In this, and in subsequent modifications of it in the "Catalogues" of the British museum, he borrows largely from Wagler (noticed below) and contemporary writers.

Oken, in his "Physiophi-losophy" (Ray society, 1847), gives a classification, elaborated between the years 1802 and 1826, in which he places reptiles in his second province of sarcozoa, fourth circle of fleshy animals, and eleventh class of myozoa or rhinozoa; the first of the above class terms relating to the fact that typical or true muscles, of a red color, and provided with tendons, are first found in reptiles, and the last to the equally important fact that, in the genetic development of the organs of sense, the nose in reptiles, first in the animal series, opens into the mouth, permitting the passage of air to the respiratory organs. This classification proceeds from the lowest reptiles (tailed batrachians) to the highest (crocodiles). Carus, in his "Comparative Anatomy," French translation (1828 and 1834), places reptiles in his third circle, cephalozoaires, and fifth class, cephalo-gastrozoaircs; with orders : I., branchiata (siren and proteus), having relations to fishes; II., pulmonata, the true representatives of the class, with the suborders batrachians, ophidians, saurians, and chelonians - some (ichthyosaurus and triton) approaching fishes, others (dragons) the birds, others (amphisbaena) even the worms, and others still (the tortoises) the mammalia; III., alata, related to birds, including the fossil pterodactyl.

Much of this and subsequent classifications is borrowed from Oken. Fitzinger, in 1826, published at Vienna his Neue Classification der Reptilien, rich in anatomical and physiological research; he adopts the classification of Brongniart modified by Oppel, with much of the nomenclature of Merrem. The class is divided into two orders, monopnoa and dipnoa, according as the respiration is pulmonary only or pulmonary and branchial, the first corresponding to reptiles proper, and the last to batrachians. In a table he gives some interesting affinities between reptiles and the higher and lower vertebrates; the pterodactyls, through the dragons and anolis, have some analogies with the mammal bats; the gavials and large fossil saurians connect the lizards with the cetacean dolphins; some che-lonians seem to connect reptiles with the mam-mal monotremata, and others (like the imbricated tortoise) with birds of the penguin family; in the same way the descent to fishes is made by the caecilians and the sirens.

The method of Ritgen, published in the volume for 1828 of the Nova Acta Academioe Natural Curiosorum, is based upon correct principles, but the author has attempted to unite too many distinctive characters under one head, and has in this way originated a most sesquipedalian and ill-sounding nomenclature. Wagler, in 1830, published at Munich his "Natural System of Amphibia," based essentially on their organization. He established eight orders in the class, as follows : 1, the testudines; 2, the crocodilians; 3, the lizards; 4, the serpents; 5, the angues (blindworm, etc.); 6, coecilioe; 7, ranoe (frogs and salamanders); and 8, ichthyodes (sirens, meno-branchs, &c), from their fish-like forms. He includes 248 genera. In chronological order would come here the classification of Dumeril and Bibron, whose work, Erpetologie generate, ou histoire naturelle complete des reptiles (10 vols. 8vo, 1835-50), is the most extensive ever published on this subject; though more recent observers have introduced some changes, their classification may be considered as representing, on the whole, the actual state of herpetology. When their work was commenced, in 1835, the materials at their command numbered about 850 species, which number they largely increased.

They divide reptiles into the four orders of chelonians or tortoises, saurians or lizards, ophidians or serpents, and batrachians or frogs and salamanders. McLeay, in the Horoe Entomologicoe (1819-'21), divides the animal kingdom into five great circles, each containing five smaller ones; the five groups of the class reptiles he considers to stand in the following natural order : 1, the chelonians; 2, emydosaurians, or crocodiles; 3, saurians; 4, dipod or two-footed serpents; and 5, apod or true serpents - the extremities of the column seeming to meet in the chelodina longicollis (Gray), and the whole forming a group distinguished from birds by being cold-blooded, and from amphibia by having two auricles to the heart, by undergoing no metamorphosis, and by a different method of generation. One great defect of this classification is, that it leaves entirely out of view the fossil enaliosaurian reptiles. Swainson, in his " Natural History of the Monocardian Animals" (Lardner's "Cyclopaedia," vol. ii., 1839), like McLeay, makes a distinct class of the amphibia, and divides reptiles into five orders: 1, emydosaurians, or crocodiles; 2, chelonians; 3, enaliosaurians (ichthyosaurus, etc.); 4, ophidians; and 5, saurians.

Strauss-Durckheim, in his Traite d'ana-tomie comparative (1843), divides his third class, or reptiles, into the three orders of saurians, ophidians, and batrachians, making a separate and fourth class of the chelonians, with the single order of testudinata. Stannius, in the second volume of the second edition of his "Manual of Comparative Anatomy" (Berlin, 1854-'0), in the class 17, reptilia, makes two subclasses, dipnoa and monopnoa. Milne-Edwards, in his Cours elementaire d'histoire naturelle (1855), divides the vertebrata or osteo-zoaires into two sub-branches; in 1, the allan-toidia, he places with mammals and birds the class of reptiles, with the orders chelonia, 8auria, and ophidia; and in 2, anallantoidia, with fishes, he places the batrachians, with the orders anura, urodela, perennibranchia, and coecilioe. - There are several German systems of classification, which deserve notice in regard to reptiles. Von Baer, in 1826-8, in his vertebrate or doubly symmetrical type, rises from osseous fishes to amphibia, in which lungs are formed, the branchial fringes remaining in the sirens and disappearing in the urodela and anura; thence to reptiles, which acquire an allantois, but have no umbilical cord, nor wings, nor air sacs, the last two being characteristic of birds.

Van Beneden, in his Anatomie compa-ree (Brussels, about 1855), makes reptiles and batrachians the third and fourth classes in his hypocotyledones or hypovitellians (vertebrata), in which the vitellus enters the body from the ventral side; the reptiles he divides into cro-codili, chelonii, ophidii, saurii, pterodactyli, si-mosauri, plesiosauri, and ichthyosauri; and the batrachians into labyrinthodontes, peromelia, anura, urodela, and lepidosirenia. Vogt, in his Zoologische Briefe (1851), bases his classification on the contrast between the embryo and the yolk, and makes the reptiles and amphibians the third and fourth classes in the vertebrata, or animals with the yolk ventral; in reptiles he includes the orders ophidia, sauria, pterodactylia, hydrosauria, and chelonia; and in amphibia the orders lepidota, apoda, cau-data, and anura. These classifications are important, as showing the tendency of modern zoology to combine embryological with external and structural characters, in establishing the natural divisions among animals; for full details and interesting remarks on these and other systems, the reader is referred to the "Essay on Classification'1 in Prof. Agassiz's "Contributions to the Natural History of the United States," vol. i. - T. Rymer Jones, in the article "Reptilia," in the "Cyclopaedia of Anatomy and Physiology," vol. iv., gives the following classification, considering the batrachians as a separate class : Order I., chelonia; II., sauria; and III., ophidia.

Van der Hoe-ven, in his " Handbook of Zoology " (English translation, 1858), thinks De Blainville went too far in elevating the batrachians into a class, and goes back toward the old fourfold division, adding however two orders. He divides reptiles into two sections: diplopnoa or psiloder-ma, breathing by lungs or gills and with smooth skin; and haplopnoa, breathing by lungs only, and with a scaly skin. Owen, in the "Anatomy of Vertebrates" (vol. i., 1866), makes the following subclasses in the reptilian division of the hoematocrya or cold-blooded animals, which include also the fishes : subclass 5, with orders ichthyopterygia, ichthyosaurs; sauroptcvygia, plesiosaurs; anomodontia, like dicynodon and rhynchosaurus (all of the above extinct); chelonia, tortoises and turtles; lacertilia, lizards, etc.; ophidia, serpents; crocodilia; dinosauria, iguanodon, etc.; and pterosauria, pterodactyl, etc. (the last two also extinct). Prof. T. II. Huxley, in the "Introduction to the Classification of Animals" (London, 1809, really dating back to 1864), calls the second "province" of vertebrates sauropsida, comprising reptiles and birds, the close affinity between the two being shown by such reptilian birds or bird-like reptiles as archoeoteryx. (See Archaeopteryx.) The reptiles are the second class of the province, there being four living and five fossil orders: 1, crocodilia; 2, lacertilia, as lizards, blind worms, and chameleons; 3, ophidia, or snakes; 4, chelonia, turtles and tortoises; and the following fossil : 5, ichthyosauria; 6, plesiosauria; 7, dicyno-dontia; 8, pterosauria; 9, dinosauria.

Prof. Nicholson, in his "Text Book of Zoology" (London, 1872), adopts the same classification, simply adopting Owen's names for the fifth, sixth, and seventh orders of Huxley. - First in the order of American classifications of native reptiles is that of Harlan, given in the "Journal of the Philadelphia Academy of Natural Sciences" (vols. v. and vi., 1826). He adopts Brongniart's four orders, dividing them as follows: 1, batrachia, divided into three sections according to the mode of respiration; the first has the branchial openings persistent, as in amphiuma and menopoma, the second with persistent branchiae, like siren and menobran-chus, and the third with deciduous branchiae, breathing by lungs in the adult state (salamanders, frogs, and toads); 2, ophidia, with six North American genera; 3, sauria, with six genera; and 4, chelonia, with three families of land, fresh-water, and sea tortoises, with two, three, and two genera respectively. Dr. J. E. Holbrook, in his "North American Her-petology" (5 vols. 4to, 1842), adopts the four orders of chelonia, sauria, ophidia, and batra-chia; in the chelonia, sauria, and tailless batrachia, he follows essentially the arrange-ment of Dumeril and Bibron; in ophidia he prefers Cuvier's classification; and in the tailed batrachia, a system partly from Cuvier and partly from Fitzinger. His work is very valuable to the American student, both for its lucid descriptions and excellent illustrations.

Messrs. Baird and Girard have published in the "Reports of. the Smithsonian Institution" (1853) a catalogue of North American serpents, of the families crotalidoe, colubridoe, boidoe, and typhlo-pidoe; of 35 genera they make 22 new, and of 119 species 54 new. Mr. Baird has published a revision of the North American tailed batrachia, with new genera and species, in the " Journal of the Academy of Natural Sciences" (vol. i., 2d series, 1850), adopting the two groups of Dumeril and Bibron, atreto-dera and trematodera. In the same journal, vol. iii., 1858, is a paper by Dr. E. Hallowell on the caducibranchiate batrachians. Mr. J. Le Conte, in the " Proceedings of the Academy of Natural Sciences " (vol. vii., 1854), gives a catalogue of the American testudinata, which he divides into three families, corresponding to sea, fresh-water, and land tortoises. Other catalogues of American reptiles, more or less extensive, are scattered through the scientific journals. De Kay, in the " Natural History of New York" (1842), divides its reptiles into the orders: 1. chelonia, with family chelonidoe;. 2, sauria, with families scincidoe and agamidoe; and 3, ophidia, with families coluberidoe and crotalidoe. The amphibia he divides into the families ranidoe, salamandridoe, sirenidoe, and amphiumidoe.

Prof. Agassiz, in his "Essay on Classification " (1857), insists on the separation of the amphibians as a class from the reptiles, from the different manner in which their structural plan is carried out; the former breathe by lungs or gills, undergo metamorphosis, lay a large number of small eggs, and have a naked skin; the latter are covered with horny scales, lay few and comparatively large eggs, breathe by lungs, and undergo no marked transformation; these differences require special ways and means in framing their structure, which ought to rank them as distinct classes. Prof. Agassiz divides his fifth class, or amphibians, into three orders, coecilioe, ichthyodi, and anura: and the sixth and higher class, reptiles, into four orders, serpentes, saurii, rhizodontes, and testudinata. In part ii. of his first volume, above referred to, he divides the order testudinata into the suborders: 1, chelonii (Opp.), with two families, chelonioidoe and sphargididoe; 2, amydoe (Opp.), with seven families, trionychidoe, chelyoidoe, hydraspididoe, chelydroidoe, cinosternoidoe, emydoidoe, and tes-tudinina. A large part of the first and all of the second volume is taken up in the consideration of the whole subject of North American testudinata, with numerous illustrations. - The above are the principal systems of her-petology, and are sufficient to show the progress of this branch of zoology, and its gradual approach toward a natural method of classification.

Those who wish to pursue the subject into its details are referred to the list of authors in the work of Dumeril and Bibron, and in the foot notes to the essay of Prof. Agassiz.