472 GEOLOGICAL SURVEY OF THE TEEEITORIES. 



distinction. It is a more slender fisli than any here described, approacli- 

 ing more nearly the proportions assigned by Girard to tbe S. virginalis. 

 From this species the numerous branchiostegals. more distinctly forked 

 tail, &c., distinguish it. 



The head is elongate, but not wide, and the muzzle descends regu- 

 larly, but not abruptly, to the lip margin. The eye is contained in it 

 1.5 times and enters the head five times in a specimen of the size of those 

 of S. pleiiriticus, where it enters four times, as well as in larger animals. 

 Tbe interorbital region contracts at the front i^art of the orbits so 

 as to be little wider than the long diameter of the latter. Tbe frontal 

 keel extends the whole length of the vertex, and is very conspicuous; 

 it is most elevated posteriorly. The maxillary extends to beyond the 

 orbit. The dorsal fin is equidistant between the end of the muzzle and 

 the base of the marginal radii of the caudal fin, therefore nearer the 

 former than to the termination of the lateral caudal scales. 



Eadii, Br. XII, XI ; T>. 11-11 -, A. 11-11. 



The ground is light, perhaps rosy in life, ond is marked with round, 

 black spots, sparsely but equidistautly distributed over tbe whole body. 

 Tbe dorsal and caudal fins are spotted, but rather sparsely; tlioseof the 

 former being arranged in two or more longitudinal series. There are 

 indications that the fins and sides of the head were crimson, and that 

 tliere were large spots of the same color on the middle of the sides. 



Two specimens of uncertain locality ; fragments of, perhaps, a third 

 from the Yellowstone Geyser Basin. 



Another species of trout was obtained from Carrington's Lake, Mon- 

 tana, but the specimens are in too bad a state for deteruunatiou. 



Plectospondyli. 



SE3I0TILUS CORPORALIS, Mitch. 



Crow Creek, at Camp Carliug. 



Ceraticiithys NUBILUS, G. ; Argyreus miMus^ G., (U. S. Pac. E. E. 

 Surv., X, p. 244.) 



Tbis species has the i)hysiognomy of the genus to which Girard re- 

 ferred it, but the premaxillary is projectile and the ui)per lip separated 

 from the muzzle by a fold. This is the only point of distinction yet 

 stated by which tbe two genera may be separated. Teetb, 4.L-l/.4 ; 

 barbels inconspicuous. Axils of the fins crimson. 



Grass Creek, Idaho. Collection No. 4. 



Apocope, Cope, ^c«. «or. 



Teeth of the raptorial type, 4.1-1.4, without grinding surface. Bar- 

 bels present ; upper lip separated from muzzle by a fold. Anterior 

 part of the lateral line only present. 



Apocope carriis'gto^^ii, Cope, sp. now 



This is a small species allied to the last, but the muzzle is broader 

 and less prominent, and tbe mouth larger. Tbe muzzle is quite obtuse 

 in profile and overhangs the mouth very little, and the end of the max- 

 illary bone does not quite reach tbe line of the margin of the orbit. 

 Barbels minute; teeth, 4.1-1.4; isthmus wide; eye a little smaller tbaii 

 one-fourth tbe length of the head, and 1.5 times in interorbital width. 

 Scales, 10-GO-ll. Dorsal fin originating behind the point above the ven- 

 trals, and markedly nearer the basis of the caudal than tbe end of the 



