PLEOTOSPONDYLI OYPEINIDAB H. NIGELLUS. 



671 



Greatest depth equal to length of head and one-fourth of total length 

 without the caudal fin. Mouth terminal ; upper jaw overlapping ; maxillary 

 bone reaching line of orbit. Profile gently descending from nares. Mouth 

 more than a semicircle ; lower jaw hard, but not so attenuated as in the 

 species of Hybognathus. Eye not large, 4.1 times in length, of head, 1.3 

 times in muzzle and interorbital width. First dorsal ray above first ven- 

 tral. Radii : D. I. 8 ; A. I. 7 ; V. 8, reaching anal ; pectorals extending 0.66, 

 the distance to the ventrals. Dorsal and anal fin long. Dorsal nearer the 



17 



end of the muzzle than the caudal fin ; caudal fin short. Scales, 5i, present 



15 



on median lines above and below. 



Color dark iron-gray above (whence the name) ; a darker band of the 

 same along the side above the lateral line, extending to the end of the muz- 

 zle, and through the caudal radii to the notch of that fin. Total length, 

 0.84 ; length to basis of caudal fin ; 0.70 ; length to first dorsal ray, 0.33. 



The plate affords a view in profile of the species and of the ventral aspect. 



HYBORHYNCHUS NIGELLUS, Cope, sp. nov. 



This Cyprinoid resembles a Pimephales, but possesses a complete lateral 

 line. Teeth, 4-4. Alimentary canal elongate, less so than in the H. siderius. 



8-9 



Scales narrowly exposed, 15. Form stout with moderately convex dor- 



5-G 



sal outline ; head wide, the muzzle abruptly truncate. Mouth terminal, 

 very small, oblique ; the end of the maxillary not reaching the line of the 

 orbital border. Diameter of eye one-fourth length of head, one-half inter- 

 orbital width, and a little less than length of muzzle. Two osseous ridges 

 on front, each extending backward from inner posterior border of nares ; 

 another short one above each postorbital region. Length of head entering 

 total without caudal fin 3.8 times, and equal to greatest depth of body. 

 Isthmus moderately wide. Radii : D. I. 8 ; osseous ray very distinct, as in 

 other species ; A. I. 7 ; V. 8. The fins are small ; but while the pectoral 

 does not reach the ventral, the latter reach the anal. 



