Eastman : A New Species of Helodus. 489 



teeth of Psephodiis, CoiJilimhis and possibly still other forms are 

 generically indistinguishable from those of Helodus ; and as shown 

 by! Dr. Traquair, the teeth described as '■'•Helodus'''' planus and 

 *' Lophodus " didyvius belong to the mouth of one and the same fish, 

 that to which Agassiz first gave the name of Cochliodus fuagnus, and 

 now known as Psephodus luagmis.^ In the same way the present writer 

 has been able to identify the arched series of teeth named Helodus 

 coxamis by Newberry as representing in reality the symphysial denti- 

 tion of Cochliodus latus Leidy.'' 



In view of these considerations there are at present no valid means 

 for determining the precise relations of either the teeth which are here 

 regarded as a new species of ^^ Helodus,^' or those which accompany 

 the new form in the same horizon and locality, previously made 

 known by Newberry under the title of H. gibbei'ulus. From other 

 provisional species of Helodus and Chomatodus the form under dis- 

 cussion is distinguished by its transversely wrinkled coronal surface, 

 without either a longitudinal elevation or median prominence. From 

 Orodus and its congeners, on the other hand, it differs in that the 

 transverse rug?e are not interrupted by a longitudinal crest or furrow, 

 as well as by the absence of median elevations. 



Horizon and Locality. — Meadville upper limestone (base of the 

 Waverly) ; Cemetery ravine, Meadville, Pennsylvania. Collected by 

 Mr. William Millward, of Peking, China, to whom thanks are due for 

 the privilege of studying the typical material. 



1 Trans. Geo!. Soc. Glasgcno (1884), Vol. VII, p. 396; also Geol. Mag. (i885), 

 dec. 3, Vol. II, p. 344. 



^ Anier. Nat. (1900), Vol. XXXIV, p. 582, and Bull. Museum Comp. Zool. 

 (1903), Vol. XXXIX, p. 203. 



I 



