This section is from the book "General Outline Of The Organization Of The Animal Kingdom, And Manual Of Comparative Anatomy", by Thomas Rymer Jones. Also available from Amazon: A General Outline of the Animal Kingdom and Manual of Comparative Anatomy.
(2004). The glosso-pharyngeal and pneumogastric nerves in Reptiles supply the same organs to which they are distributed in the human subject,, the former being destined to the base of the tongue and the muscles of the pharynx, while the latter, assuming a plexiform arrangement, are appropriated to the lungs and heart, as well as to the oesophagus and the stomach.
(2005). The hypoglossal pair of the cerebral nerves, which was not met with in fishes, now becomes distinctly apparent, and, as in the higher Vertebrata, may be traced in the muscles of the tongue.
(2006). The spinal system of nerves offers no peculiarity worthy of special description. In the annexed figure, taken from Bojanus, the nerves derived from the medulla spinalis are seen to issue in the usual manner from the intervertebral foramina; and they evidently essentially correspond with the grand type of structure common to the vertebrate classes. In the apodous Reptilia, as for example in the Serpents, to attempt to divide them into the usual regions is clearly absurd; but in quadrupedal forms, as for instance in the Tortoise, the cervical nerves, the brachial plexus, from which are derived the nerves of the anterior extremity, the intercostal nerves, and those forming the lumbar and sacral plexuses are at once distinguishable, and the correspondence between their distribution in the reptile and in the human subject must forcibly strike the student who makes the comparison.
(2007). Neither does the sympathetic system of the Reptilia offer any important aberration from that arrangement with which the human anatomist is familiar. The ganglia are smaller in their proportionate size; those, indeed, of the neck and face are scarcely perceptible; but the thoracic ganglia are found in their usual positions, communicating on the one hand with the spinal nerves, and on the other giving off filaments which form plexuses around the arterial trunks, and ramify extensively to be distributed to the viscera.
(2008). The sense of touch in all the members of the class under consideration must, from the nature of their integument, be extremely imperfect: many of them, in fact, as for example the Serpent tribes, are absolutely deprived of any limbs which can be regarded as tactile organs; and even in those forms which are provided with efficient locomotive extremities, these are but ill adapted to exercise the functions of an apparatus of touch.
(2009). The cuticular investments of the body are formed of dense and unyielding materials, consisting, in the higher Reptiles, of broad horny plates or of imbricated scales. In the Amphibia, indeed, the skin is smooth, and the epidermis only forms a delicate corneous film; yet even in these the cuticle is thrown off at certain seasons of the year, as the old coat becomes too small for the increasing size of the animal, a phenomenon which in the Lizard and Serpent tribes is still more remarkably witnessed; for these animals strip themselves of their old scales as the hand would be drawn out of a glove, and cast away in one piece the entire epidermic integument, even to the film which covers the transparent cornea of the eye.
Fig. 351. Nervous system of the Tortoise. (After Bojanus).
(2010). The urinary excretion in Reptiles becomes of very considerable importance, and the structure of the kidneys and excretory ducts proportionately elaborate. The kidneys (fig. 353, o, p) are generally situated very far back, even within the cavity of the pelvis where a sacrum exists, as in the Chelonian and Saurian orders; and in these tribes they are very partially covered by the peritoneum, being firmly imbedded in the sacral region. But in the Serpents, in consequence of the elongated form of the body and the complete flexibility of every portion of the spine, the kidneys are peculiar both in their position and general structure. Instead of being placed upon the same level as in other Vertebrata, the right kidney of an Ophidian is situated much more anteriorly than the left, - a circumstance which much facilitates the packing of the abdominal viscera, and contributes greatly to ensure the free movements of the vertebral column at this place. For the same reason, the kidneys of a Serpent are divided into numerous lobes, placed in a longitudinal series upon the outer side of the commencement of the ureter, and loosely connected to each other and to the spine by cellular tissue and a fold of the peritoneum.
(2011). As relates to the minute structure of the kidneys in the Reptilia, these viscera are invariably composed of convoluted tubes, which pour their secretion into the commencement of the corresponding ureter. The ureters, of course, vary in length according to the position of the renal organs; they ultimately terminate in the cloaca (fig. 353, u) - a cavity or general outlet through which, in the female, the ova, the fasces, and the urine are discharged, and which in the male gives passage to the contents of the rectum, the secretion of the kidneys, and the semen.
(2012). In connexion with the urinary apparatus of Reptiles, it will be convenient to mention a bladder that exists in Chelonian and Amphibious reptiles, and is also found in some Saurian tribes, to which the name "urinary bladder" has been erroneously applied. This bladder, in the Tortoise (fig. 353, a) and Proteus (fig. 340, q), is of considerable size, and in the Frog forms a very capacious receptacle, having its upper part divided into two cornua. It is generally filled with a clear limpid fluid, which in the case of the Frog is forcibly ejected if the animal be alarmed; but that this fluid is not urine is obvious from the fact already stated, that the ureters open into the cloaca (fig. 353, u), and not into the bag referred to; the latter, in fact, is the unobliterated remains of the allantois of the embryo, concerning which further particulars will be given in the next chapter, and the fluid contained in it is most probably the product of cutaneous absorption*.