2 8 Bulletin American Museum of Natural History. [Vol. XIX, 



Just what Cope's A^wgmins contractus was we shall prob- 

 ably never know. Prof. E. A. Popenoe, who has charge of 

 the collection of the Agricultural College at Manhattan, Kan- 

 sas, informs me that he is unable to find any traces of such 

 vertebrae as Cope described. The type being lost, it seems 

 proper to accept Cope's Anoguiiiis on the definition given of 

 it. When it becomes necessary to divide the genus as thus 

 defined, it will be time to consider whether or not Anogmius 

 is indeterminable. 



Recently Dr. Loomis {op. cit., p. 254) has made Cope's 

 Anogmius (spelled, however, Agnomius) a synonym of Os- 

 meroides Agassiz. Mr. Woodward properly, as it seems to 

 me, does not follow this identification. So far as we know, the 

 species of Anogmius have an elongated dorsal fin, while 

 Osmeroides (Holcolcpis) has a short dorsal. There exist un- 

 doubtedly many other distinctive characters. 



Dr. Loomis (op. cit., pp. 229, 235, 252) has described the 

 new genera Thryptodus, Pseudothryptodiis , and Syntegmodus. 

 Stewart in his work referred to, p. 391, has expressed the 

 opinion that the first two genera mentioned are synonymous 

 with Anogmius. Dr. A. S. Woodward (Cat. Foss. Fishes, IV, 

 pp. 84, 85) regards all three as closely related to Plethodus. 



There are so many structures common to the genera 

 Plethodus, Anogmius, Thryptodus, Pseudothryptodus, and 

 Syntegm.odus , that it appears evident that they are all closely 

 related, and some of them are quite certainly identical with 

 others. All appear to have an upper grinding plate developed 

 on the parasphenoid and one or more lower plates developed 

 on the median bones in the floor of the mouth. These plates 

 are composed apparently of dense bone, and are often, if not 

 always, furnished with pits, sometimes shallow, sometimes 

 deep. The maxilla forms a considerable part of the boundary of 

 the mouth, the bones about the mouth are similarly sculptured, 

 and, so far as we know, the rear of the skull is similar in all. 



Plethodus appears to be characterized by coossification of 

 the premaxillae and ethmoid and the possession of a lower 

 dental plate composed of a single bone. The upper and 

 lower plates are smooth or furnished with shallow pits. 



