438 GEOLOGICAL SURVEY OF THE TERRITORIES. 



interorbital width. Profile, plane; parietal region wide; muzzle de- 

 scending; upper lip projecting a little beyond lower; end of maxil- 

 lary bone reaching line of orbit. Twelve scales in front of dorsal fin. 

 Least depth of caudal j>ed uncle two and a half to three times in length 

 from first anal ray. Eadii, D. I. 8 ; V. 8. Pectorals nearly reach ven- 

 trals ; ventrals reach vent. Dorsal nearer end of muzzle than basis of 

 caudal. Length, M. .05. 



Light olivaceous, below paler; a silver lateral band and small dark 

 dot at base of caudal fin. No dark dorsal band. 



From near St. Joseph, Missouri. From the Mus. Acad. Sciences, 

 Chicago. 



This Hybopsis is near the H. procne, Cope, from the East. It differs 

 in the generally stouter form, the larger head and thicker caudal 

 peduncle. 



HYBOPSIS SCYLLA, (COPE ;) Sp. nOV. 



' Belonging to the group B. (Trans. Amer. Philos. Soc., 1866, 380) of 

 this genus, and therefore allied to H. stramineus and H. procne, Cope. 

 It differs from the former in its more slender form, and from both in the 

 increased number of longitudinal series of scales. 



Head 4.5 times in length without caudal fin; eye 3.5 times in head; 

 scales 6-34-4. A. I. 7. 



This species has a short head with obtuse muzzle. The lips are equal 

 and the mouth slopes a little downward, the end of the maxillary reach- 

 ing the line of the interior margin of the orbit. Length of muzzle .75 

 diameter of eye, which is little less than interorbital width ; teeth 4-4 ; 

 depth of body at first dorsal ray 4.6 times in length to basis of caudal ; 

 at caudal peduncle equal from orbit to opercular border. Ventral fin 

 originating below D. I. Pays, D. I. 8, A. I. 7, Y. 8; lateral line slightly 

 decurved medially. Total length, M. .0545. Color silvery with silver 

 lateral band, marked with black points, which are especially abundant 

 on the side of the muzzle. From Eed Cloud Creek, a tributary of the 

 Platte. 



HYBOPSIS EGREGIUS, (OIRAKD.) 



(Tigoma.) United States Pacific Railroad Reports, X, 291. 



What I suppose to be this species presents a well-marked grinding 

 surface on one tooth (the second) on each side. There is nothing to dis- 

 tinguish Girard's Tigomw, with this surface developed, from my section 

 D of Hybopsis. (Trans. Amer. Philos. Soc, 1866, 382.) These species 

 are his T. gibbossa, T. nigrescens, T. pulchra, and T. crassa. The teeth 

 are 4.1(2)-1(2).4, and the mouth more or less oblique. They cannot be 

 separated, as a genus, from Hybopsis. The Tigomce, without mastica- 

 tory surface, are closely allied to the Clinostomi, from which they differ 

 in having the teeth 4.2-2 .4 instead of 4.2-2.5. Some of Girard's Tigomce 

 appear to be true Glinostomi. Five specimens from Green Eiver. 



PHOTOGENIS PIPTOLEPIS, (COPE ;) Sp. nOV. 



This species has much the physiognomy of Ceratichthys dissimilis, Kirt., 

 and is allied to the same genus. Dorsal region alongside and in front 

 of the dorsal fin, scaleless ; scales at dorsal, 3-4 — 36 — 2-3. Eadii, D. 1.7, 

 A. 1.8, V. 7. Teeth, 4.1-1.4 ; head, one-fourth length without caudal ; 

 depth, 4.66 times in the same ; eye oval, diameter a little less than 

 length of muzzle, 3.5 times in length of head and a little less than in- 

 terorbital diameter; the mouth is nearly horizontal, and the muzzle 



