Cockerell and Callaway — Fishes of the Genus Xutropis. 195 



Hydropiii.ox Jordan. 



From tlii« we have separated N. coccogenis as a subgenus Coccogenia, 

 lint for convenience of comparison we throw it into the following table: 

 Small tisli, about 2 inches long, with l»road, dark, very conspicuous lat- 

 eral band; scales subcircular or even longer than broad, sculi)ture 

 distinct, radii o to S, circuli irregular .... X. cliah/bcrvs (Cope). 



Buckhead Creek, ]\Iillen, (Ta. 

 Larger fish (over .S inches), with silvery sides ami no dark band. 



.Scales extremely broad, with radii IG to 20 . . . X. coccogenis (Cope). 



TellicoK., Tenn. 

 Scales circular or nearly so, the base flattened, radii about (>, circuli 



regular X. zo)tatus (Agassiz). 



White River, Arkansas. 

 X. iiniversitafis Evermaini ik Cockerell (N. zonatus var., Univ. of Colo- 

 rado Studies, Y. 1908, p. 170). 



Y. zonalns and chalyhtrns are very distinct, ami may not l)e properly 

 associated in the same group. 



NoTROPis s. str. 



Although we have a number of species of this group, the range of varia- 

 tion in the radii of the combined series is remarkalily small. Instead of 

 being the stem-form of the genus, as its name might suggest, this appears 

 to be the last of the end-forms. 



X. jejunus, leuciodus, stilbius, telescopus, athcrinoides and swaini are 

 all small fishes (l)ut our athcrinoides must be young) with large eye and 

 broad lateral silvery band, very much alike. X. arge looks different; 

 much larger (ours 4% inches), with dark lateral band. X. scopifrr in 

 intermediate in size, with sides silvery; a deeper-bodied fish than arge, 

 with convex back (back of arge is almost straight). X. arge has scales 

 feebly sculptured, with few radii; scopifer has them strongly sculptured, 

 the radii variable but often more numerous. X. arge has the distance 

 from nostril to eye greater than breadlh of nostril; scopifcr has it less. 

 The snout is shorter in scopifer. 



The six species which are so much alike, separate upon external exami- 

 nation as follows: 

 Northern, deeper-bodied species, the sculpture of the scales distinct. 



Eye larger, diameter 4 mm X. atherinoides Rafinesque. 



Medicine Hat, Canada. 



Eye smaller, diameter 3 mm X. jejunus (Forbes). 



Red River of the North, Moorehead, INIinn. 

 Southern species, slender-bodied; hind part of head above black or plum- 

 beous. A conspicuous black spot at base of caudal fin ; sculpture 

 of scales weak. 

 Scales of lateral line witli little dark spots . . . A', telescopus (Cope). 



Indian Creek, Cumberland Gap, Tenn. 

 Scales of lateral line without such spots .... X. leuciodus (Cope). 



Tenne.ssee. 



