Foraminifera

For the first time these animals assume considerable importance in the earth's economy. Many genera which are still living had representatives in the Carboniferous seas, but the most conspicuous and abundant is the extinct Fusu-lina (XII, 1, 1 a), a very large kind, with shells resembling grains of wheat in size and shape. This genus is especially developed in the Upper Carboniferous, while Schwagerina characterizes the uppermost part of the system. In the Salem limestone of Indiana, a well-known building stone, of the Mississippian series, Endothyra (XI, 1) is abundant.

Sponges are common, though rarely found in good preservation.

Ccelenterata

Corals were abundant, and contributed largely to the limestones; the genus Lithostrotion (XI, 2), which is peculiar to this period, plays a very prominent part. Lophophyllum is found in the Upper Carboniferous.

Echinodermata make up an exceedingly important part of the Carboniferous marine fauna. The Cystoids have disappeared, but the Blastoids have developed in great numbers, and are highly characteristic of the Carboniferous limestones. As the group is entirely extinct and does not pass beyond the Carboniferous system, its structure has much that is problematical about it. The delicate, symmetrical body, or calyx, which is carried on a short stem, is composed of a small, definite number of plates, and has five "pseudo-ambulacral" areas, which look much like the ambulacra of a sea-urchin. In exceptionally well-preserved specimens numbers of delicate pinnules are attached to these areas. The must abundant genera are Pentremites (XI, 4-5) and Grana-tocrinus.

Plate XI. - Lower Carboniferous Fossils.

Figs, i, ia, Endothyra baileyi Hall, x 9, St. Louis, side and end views. 2, Lithostro-tion canadense Castelnau, x 1/2t St. Louis. 3, Eutrochocrinus christyi Shumard, x 1/2, Burlington. 4, Pentremites elongatus Shumard, x 1, Burlington. 5, P. conoideus Hall, x 1, Keokuk. 6, Melonites muhiporus Norwood and Owen, x 1/2, St. Louis. 7, Archituedes avortheni Hall, + 1/2, Keokuk. 8, Spirifer grimesi Hall, x 1/4, Burlington, 9, Reticularia pseudolineata Hall, x 1/2, Keokuk 10, Syringothyris subcuspidatus Hall, Keokuk, 11, Productus magnits Meek & Worthen, x 1/4, Keokuk. 12, Brancoceras ixion Hall, x 1/2, Kinderhook. 13, 13a, Prodromites prezntaturus Smith and Weller, x 1/2, side and end views. 14, Petalodtts linguifer Newb. and Worth., x 1/2, Kaskaskia.

All other Echinoderms of the Carboniferous seas were utterly insignificant as compared with the Crinoids, which reach theit culmination of development in this period: more than 600 species have been described from the Carboniferous limestones of North America alone. Certain localities, such as Burlington (la.) and Crawfordsville (Ind.), are famous for the vast numbers and exquisite preservation of their fossil sea-lilies. The crinoid remains occur in such multitudes that in many places the limestones are principally composed of them; in such places they must have covered the sea-bottom like miniature forests. But this extraordinary abundance is not general over North America, but characterizes the Central States only and Mississippian time, especially the Osage. All the Carboniferous Crinoids, like those of the earlier periods, belong to the extinct order Camerata, none of which passed over into the Mesozoic era. Of the long list of Crinoids found in the rocks of this system may be mentioned Actinocrinus, Platycrinus, Rhodocrinus, Eutrochocrinus (XI, 3), Onychocrinus, Aesiocrinus, and Eupachycrinus (XII, 2).

The Echinoids, or sea-urchins, are still far less abundant than the Crinoids, but they are much more numerous and varied, and of larger size than they had been before; some, indeed, are as large as any sea-urchins that are known from any period. The Carboniferous sea-urchins are, like those of the preceding periods, members of the ancient and now extinct subclass, Palceechinoidea, and the commonest genera are Melonites (XI, 6), Oligoporus, and Archceocidaris. In addition to these should be noted the presence of the modern subrlass, Euechinoidea, as the ancestor of the still existing genus Cidaris is reported from the Carboniferous.

The first known Holothuroidea, or sea-cucumbers, date from this period.

Arthropoda

The Trilobites have become rare and are soon to die out altogether; most of the species belong to the peculiarly Carboniferous genera Phillipsia (XII, 21) and Grifithides, but the Devonian Proetus still persists. The Eurypterids continue, even into the coal measures, where they lived in the fresh-water swamps, but they cannot compare in size or numbers with the great Devonian forms. The horse-shoe crabs are represented by Prestwichia. Phyllopods and Ostracods are abundant, and in the coal measures are found crustaceans formerly incorrectly referred to the Decapods, which they resemble; of these Anthracopalcemon is the best-known genus.

Centipedes and Scorpions are much commoner than in the Devonian, and the first of the true Spiders are found here. Insects likewise show a great increase in numbers, though the Orthopters and Neuropters are still the principal orders represented. Many of the Carboniferous insects are remarkable for their great size, some of them measuring 30 inches across the extended wings, and more remarkable is the fact that several insects of this period had three pairs of wings, corresponding to the number of legs. The character of the vegetation has a very direct influence upon insect life, and the monotonous, flowerless Carboniferous forests could not have supported butterflies, bees, wasps, ants, or flies. No insects of these groups have been found in the rocks of that system, and it is not yet certain whether even beetles were then in existence.

The land life of the Carboniferous seems to be very much more varied and luxuriant than that of the Devonian, and it probably was so in reality. It must be remembered, however, that the immense development of fresh-water and marshy deposits in the Carboniferous was much more favourable to the preservation of such fossils than any conditions that the Devonian had to offer. Part, at least, of the striking difference in the terrestrial fossils of the two periods is to be accounted for in this way.

Subguadrata Shumard, x 1/2. 13, Aviculopecten occidentalis Shumard, x 1/2. 14, Bake-vellia parva Meek and Hayden, x 2, Permian. 15, Pleurophorus stcbcuneatus M. and H., x 1, Permian. 16, Pseudomonotis hawni M. and H., x 1/2. Permian. 17, Bellerophon fercarinatus Conrad, x 1. 18, Pleurotomaria sphcerulata Conr., x 1/2. 19, 19a, Strapa-rolluspronodosus M. and W., x 1/2. 20, Waagenoceras cumminsi White, x 4/5. 20a, The same, a suture line, Permian. 21, Phillipsia major Shumard, x 1/2.

Plate XII. - Upper Carboniferous and Permian Fossils.

Upper Carboniferous. Fig i, Fusulina cylindrical Fischer, x 5/4. 1a, F. secalica Say, x 5/2, longitudinal section. 2, Eupachycrinus verrucosus White and St. John, x 1/2,3 Derbya biloba Hall, x 1/2. 4, Meekella striatocostata Cox, x 1/2. 5, Chonetes veneuihatia Norwood and Pratten, x 2. 6, Productus costatus Sowerby, x 1/2. 7, Spirifer cameratus Morton, x 1/2. 8, Seminida argentea Shephard, x 1/2. 9. Dielasma bovidens Morton, X 1/2. 10, Pugnax uta Marcou, x 2. 11, Monopteria longispina Cox, x 1/2. 12, Myalina.