230 ON THE DISTRIBUTION OF FEESH-WATER FISHES 



Undoubted sjDecimens of this species in the British Museum are included by Dr. 

 Giinther in the vii vol. Catalogue Fishes Brit. Museum, as individuals of Ceratichthys 

 biguttatus. It is not difficult to perceive how this error has occurred, as the 

 external technical features of the two are alike in many respects. The resemblance is, 

 however, superficial, for the two belong to different groups of genera, — Ceratichthys 

 being allied to Gobio, and Photogenis scabriceps to Leuciscus, The latter is a 

 small species, the former a large one ; they differ in osteological characters, as the 

 form of the preorbital bone, etc. No one who has seen the two living in the same 

 streams can ever confound them, as their coloration is totally distinct. The one 

 species is widely distributed, the other, so far as known, is confined to the Kanawha. 



HYBOPSIS Agass. 



Four species are added to this genus ; one from the Roanoke and James Rivers, 

 and three from the Holston. Two of them belong to division B (Synopsis Cyprinida3 

 Pennsylvania), or the t3'pe of H. procne, where the teeth are 4 — 4, and the mouth 

 horizontal and slightly inferior; two belong to division D, or the type of H. 

 chalybajus, where the teeth are 2-4 — 4-2, and the mouth oblique and the 

 mandible more elongate. 



Division B. 

 a. Pectoral fins not attaining the ventrals. 



Form elongate, depth 5 times, head 4-25 or 4-5 in length. Eye 



equal muzzle, 3-5 (in young 3-25) in head, equal prasorbital 



width; scales 5 — 33 — 2, 14 before dorsal fin. Anal rays 7, . H. longiceps. 

 Form elongate, head larger, broad and rather flat, 4 times in 



len"-th; depth 5'5 to 6 times in same. Eye large, diameter 



"•reater than len2;th muzzle, three times in head, less than 



preorbital width; scales 5(4) — 37 — 3: 15 rows anterior to 



dorsal; anal radii 9, H. SPECTRUNCC7LTJS. 



Division D. 

 Preorbital bone longer than deep ; operculum posterior margin 



shorter than inferior; eye equal length muzzle, 3-5, 3-75 in 



head; latter, 3-75, 4 times, depth 4-75 — 5 times in length; 



scales 7— 3S — 3 ; anal radii 9, H. rubriceoceus. 



Preorbital deeper than long; posterior margin operculum longer 



than inferior ; chin projecting beyond muzzle, ma.xillary not 



reaching line orbit. Eye 3-25 in head, equal muzzle ; head 



broad, 4 times in length ; scales large, 5 above lateral line, . H. lacertosus. 



