30 



THE EXTINCT RATRAOHIA, REPTTLIA 



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. 



EOSAURUS ACADIANUS, Marsh. 



Amer. Jour. Science, xxxiv. 1802, 1 Tab. I, [I. 



Coal measures: Joggins of Nova Scotia. 



4 R C ■■ OSil llll. 



This great order of Eteptilia corresponds with the Monirnostylica of Midler, 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- hone, may he readily understood by comparison of the accompanying figures 

 of Nothosaurus from the Muschelkalk of Germany, and Mecistops intermedins (i raves,! 

 recent, from the Orinoco, with the plate of CHdastes 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 remove 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 procoracoiil united with scapula; a distinct episternum. 

 Ribs single headed. 



*Tlie following species have been described by Leidy, who refers them to Reptilia with doubt, and says they may 

 lie fishes. As this point remains undecided, I can only allude to them here. 



G Y M BOBPO ND YLUS, Leidy. 

 Proceedings Acad. Nat. Sciences, Philada., 1858. — 178. 



Y.M B( )S I ■( ) N I ) V I ; I i S I > I S< !( )S 1 1 S, Leidy, I. c. 

 :' Triassic of Humbuldt Co., and of the Toiyabe Range, Nevada. 



CYMBOSPONDYLUS PETRINUS, Leidy, I. c 

 ? Triassic ; Humboldt, Nevada,. 



t This cut is taken from the type specimen of Mecistops bathryJiynchus, in Mus. Academy. The Nothosaurus is 

 the N. andriani or a nearly allied species. T am not quite positive that the number of alveoli on the maxillary bout- 

 is exactly correct. 



