GEOLOGICAL SURVEY OF THE TEERITOEIES. 475 



Color deep purplisli-brown, with ratlier scattered, irregular, yellow 

 si)ots with black Diargins j rather paler below. 



From the Eio Grande, at San Jose, Costa Eica. Dr. Van Patten. 



This species, in general proportions, is a little more slender than the 

 last, but in general apx>earance, as size and coloration, can scarcely be 

 distinguished from it. It Ls a curious case of mimetic analogy. 



SiBOMA ATRAJaiA, C, (U. S. Pac. R. E., Eep. X, 297.) 



Abundant in Grass Creek, Idaho. Sihoma differs from Clinostomus in 

 the anterior j)ositi,on of the dorsal fin. Collection No. 7. 



Myloleucus, Cope, gen, nov. 



Teeth raptorial, but with well-developed masticatory surface, 5-4 in 

 outer row. No barbels ,• lateral line well developed. Dorsal fin above 

 or in front of line of ventrals. 

 ^ This genus is Sihoma, with developed grinding surfaces of the teeth. 



Myloleucus pulverulentus, Cope, sp. nov, 



Form stout 5 head short, muzzle not decurvedj mouth terminal, 

 slightly descending, the maxillary bone nearly attaining the anterior 

 line of the orbit. Head 3.75 times in length, exclusive of caudal; depth 

 three and a half times. Eye 4.2 times in head, once in muzzle. Pre- 

 orbital bone deeper than long. Scales, 13-58-9. Eadii, D. I. 9 ; A. II. 7. 

 Caudal well forked. Length, 3J inches. 



A dark plumbeous band extends from the origin of the lateral line 

 above to the caudal peduncle, and on it to the caudal fin. Below this 

 the color is silver^^, thickly dusted with black dots; above it is an olive- 

 yellow band; then a dark dorsal region, all dusted. Sides of head sil- 

 very, dusted. Fins unspotted. 



Numerous specimens from the Warm Springs, Utah; tyi^e No. 6. 



Clinostomus pandora Cope, sp. nov. 



This species is nearly a Siboma^ in consequence of the position of the 

 dorsal fin being so little removed from the vertical above the ventrals. 

 Dentition refers it to GlinostoniuSj while its appearance is that of a 

 Ceratichthys or Semotihis. I adhere to the technical characters until 

 others are found which will give us the clew to the truer affinities. 



Shape fusiform, head small, one-fifth of total length, (or fourth with- 

 out caudal fin,) broad, and rather flat at the muzzle. The latter does 

 not project, and the lips are equal. Maxilla not attaining the line of 

 the orbit by some distance. Eye small, 6.25 times in length of head, 

 twice interorbital width. Scales, 17-61-9, small in front of dorsal fin. 

 Eadii, D. I. 8; A. II. 8. Isthmus moderately wide; depth of body 4.2 

 times in length without caudal. Dorsal tin nearer basis caudal than end 

 of muzzle. 



General color silvery, above (in spirits) brownish. A broad, ill-defined, 

 lateral band, from epiclavicular region to basis of caudal fin, above the 

 lateral line. Length of type specimen, 8 inches. Collection No. 11. 



From Sangre dc Christo Pass, from a tributary of the Eio Grande. 



Clinostomus hydropiilox, Cope, sp. nov. 



This species and the following are typical forms of the genus, and in- 

 teresting as the first that have been detected west of the Missis- 

 sippi Eiver. Length of head 4.75 times in total, exclusive of caudal 

 fin; depth of body 4.5 times in same. Eye 5 times in head, one and a 

 half times in interorbital width. Front straight; lower ja\Y iHojecting 



