Page:Synopsis of the Exinct Batrachia and Reptilia of North America. Part 1..pdf/34

 30 THE EXTINCT BATRACHIA, REPTILIA EOSAURUS, Marsh.* This genus, as suggested by Huxley, may be the type of a peculiar division of the Batrachia. There appears to be some probability of this being found to be the case, though present evidence is in favor of Prof. Marsh's location here. EOSATJRUS ACADIANUS, Marsh. Amer. Jour. Science, xxxiv. 1862, 1 Tab. I, IL Coal measures : Joggins of Nova Scotia. A It ( II OSAUHIA. This great order of Reptilia corresponds with the Monimostylica of Mfillcr, without the Testudinata. The latter differ too much in the vertebral and sternal structure to be retained in it. The important feature which characterizes the order, the close sutural attachment of the quadrate bone, may be readily understood by comparison of the accompanying figures of Nothosaurus from the Musthelkalk of Germany, and Mecistops intermedius Graves, j' recent, from the Orinoco, with the plate of Clidastes propython, at the end of the volume. The order embraces that large series of forms which seem to be equidistant between all the extremes of the Reptilian type. It therefore is not a strictly homogenous group ; yet its subdivisions do not appear, with present knowledge, to be sufficiently marked, to render it proper to esteem them of equal value with the other orders here enumerated. This is a usual difficulty of classification ; we express it, and do not remol e it, by admitting the existence of a protean type in a genus of species, a family of genera, a class of orders, etc., etc. The suborders are as follows : Limbs without flexible articulation ; natatory ; no femoral trochanters ; no sacrum. A procoracoid united with scapula ; a distinct episternum. Ribs single headed.
 * The following species have been described by Leidy, who refers them to Reptilia with doubt, and says they may be fishes. As this poiut remains undecided, I can only allude to them here. CY3IBOSPONDT MIS, Leidy. Proceedings Acad. Nat. Sciences, Philada., 1858.-178. CY3IBOSPONDYLITS PISCOSUS, Leidy, 1. c. 2 Triassic of Humboldt Co., and of the Toiyabe Range, Nevada. Ct:NIBOSPONDYLITS PETRINUS, Leidy, 1. c. ? Triassic ; Humboldt, Nevada. t This cut is taken from the type specimen of Necistops bathrykynchus, iu Mus. Academy. The Nothosaurus is the N. audriani or a nearly allied species. I am not quite positive that the number of alveoli on the maxillary bone is exactly correct.