1883.] NATURAL SCIENCES OF PHILADELPHIA. 143 



specific characters somewhat difficult to unravel. Teeth of species 

 of this genus occur in the pliocene lake deposits of the Great 

 Basin. 



Myloleucus gibbarcus Cope. AlhumojyB gihlarcns Cope, Proceeds. Amer. Philis. 

 Society, 1877, p. 230. Anchybopsis breviitrctis Cope, 1. c, p. 229. 



The presence of four teeth on the right pharyngeal bone of 

 specimens referred to Alburnops, as above, is not established ; and 

 the other characters point to the specific identity of the indi- 

 viduals included under the two names cited. It was abundant in 

 a fossil state at Fossil Lake, Oregon, whence I have obtained 

 about twenty pharyngeal bones of both sides. First discovered 

 by Chas. M. Sternberg. 



The recent species may be distinguished as follows : — 

 Scales 11-12 — 51-5 — 6-7; anal rays I. 8; head 3*5; depth 3-5 to 



4 times in length, M. formosus. 



Scales 10 — 47-50 — 5 ; anal rays I. 8 ; head 3*5 ; depth 4 times in 



length. M. parovanus. 



Scales 9-46-4 ; anal rays I. 9 ; head 3-75 ; depth 4*5 times in 



length. M. thallassinus. 



Myloleucus formosus Girard. Jordan, Synopsis Fishes N.A., p. xxi. Leucus formoxtts 

 Jordan, Report Capt. G. M. Wheeler, Expl. W. 100th Mer., 8vo, 1878, p. 193. 



Specimens of this fish from Silver Lake represent a form of 

 the species allied to the M. obesus, in the greater depth of the 

 body than those found in the Chewaucan River and the Warner 

 Lakes. In the first named, the depth enters the length 3*5 times ; 

 in the last two, four times. The Silver Lake specimens diverge 

 from the types in having the scales a little larger. They are 

 thus counted in the three sets of specimens : — 



Silver Lake 11 — 51-3 — 8; Chewaucan 11-55-7; Warner Lake 

 12 — 54-5 — 7. The largest specimen is from Warner's Lake and 

 measures 8 J inches in length. ' ' 



Myloleucus parovanus Cope. Zoology Wheeler's Expl. Surv. W. lOOrh Mer., p. 669. 



This species was originally described by me from the Beaver 

 River of Utah. It now appears that is the most abundant 

 cyprinoid of Goose and Klamath Lakes. It reaches a length of 

 10 to 12 inches, and forms a large part of the food of the great 

 flocks of various species of fishing-birds which live at those lakes. 

 Its specific characters are constant in a large number of indi- 

 viduals. Prof. Jordan identified this species with the M. bicolor 



