ISOSPONDYLI. 71 



no concentric grooves ; the cells are smaller. In Vastres the exposed sur- 

 faces are still more rugose; in large examples quite honeycombed. 



The specimens represent an individual of 3 or 4 feet in length. Dis- 

 covered at the fish slate cut on the Green River, on the line of the Union 

 Pacific Railroad by Lucius E. Ricksecker, C. E. 



Dapedoglossus testis Cope. 



Bulletin U. S. Geol. Snrv. Terrs., 1877, p. 807 (August 15). 

 Plate VII, fig. 1 ; Plate VIII, figs. 1-2. 



Form oval, contracting subequally to the muzzle and caudal peduncle. 

 The fi-ont is gently convex and the mouth is terminal. The depth is little 

 less than half the length minus the caudal fin, and the length of the head 

 enters the same 3.4 times. The dorsal fin is shorter than the anal, and its 

 first ray stands over the sixth of the latter. The ventrals are small, and 

 extend about one-half the distance from their base to the first anal ray, which 

 equals the distance to the base of the pectoral. The latter is elongate, 

 especially the first ray, which, although jointed, as in Osteoglossum bicir- 

 rhosum, reaches nearly to the end of the ventral. Radii: D. 22-23; A. 27— 

 30. The caudal fin is slightly concave. Scales five or six series above the 

 vertebral column and seven below it. Their exposed surface is rather wide, 

 and is minutely granulated and without grooves. The cells are invisible 

 except when this sm-face is removed, and they are rather large. Vertebrse, 

 18 dorsal, 24-25 caudal. 



The orbit is rather large, and is reached by the end of the maxillary 

 bone. The suborbital bones are not much enlarged, as is the case in the 

 recent genera. Preoperculum entire ; suboperculum very naiTow. Branchi- 

 ostegals slender, rather numerous ; coracoid wide, forming a vertical keel, 

 which is not produced. Length of the longest specimen, 0™.230; of the 

 shortest, O^.IBS. 



The numerous specimens of this which I have seen differ in size, and 

 are three-fifths and less, of the dimensions of the JD. encaustus. 



As compared with the D. acutus, I notice that the dentary bone does 

 not support quite so many long teeth. I count twenty-three in the former 

 and seventeen or eighteen in the I), testis. 



From the Green River shales at Twin Creek, Wyoming, 



