298 



THE AMERICAN NATURALIST. [Vol. XXXVIII. 



Fragments of chimaeroid jaws have been previously reported 

 from the Chemung of New York State by Clarke, but 

 no specific identifications were attempted by him. At best this 

 class of remains appears to be very rare in the eastern province, 

 Ptyctodus and Rhynchodus being the only genera that are 

 known from the New York Devonian. An undescribed species 

 of the former occurs in the Corniferous hmestone of Le Roy, 

 and P. calceolus is apparently represented in the Hamilton stage 

 at Eighteen Mile Creek, near Buffalo. Detached tritors from 

 both of these localities are preserved in the Museum of Com- 

 parative Zoology at Cambridge. 



Onchosaurus Gervais. 



Syn. Ischyrhiza Leidy ; Gigantichthys Dames. 



A comparison of the type specimens of Gervais' OncJiosanrus 

 radicalism and Leidy's hchyrJiiza antiqna,'^ the former being pre- 

 ser\^ed in the collection of the School of Mines at Paris, and the 

 latter in the American Museum of Natural History in New 

 York, leaves no room for doubt that they are generically, and 

 probably also specifically identical, in which case Leidy's title 

 must be abandoned. The original of Gervais' description, 

 together with one or two duplicates, was derived from the 

 Upper Cretaceous of Meudon, near Paris, and regarded through 

 error as of mosasaur nature. The identical form occurs also in 

 the Maestricht Chalk, a remarkably fine specimen from this 

 locality being preserved in the Paris Museum of Natural His- 



The type of Leidy's genus, /. mira;^ was founded on a unique 

 tooth from the Cretaceous Greensand of Burlington County, 

 New Jersey, and supposed by the author to represent a Teleost 

 fish related to Sphyraena. The original has never been figured, 



