784 BULLETIN UNITED STATES GEOLOGICAL SURVEY. 



Pimeplialcs provielas Jordan, Cat. Fishes N. A. 419. 

 1856 — Pimejyhales fasciatus Gieard, Proc. Acad. Nat. Sci. Phila. 180. 



Pimcphales fasciaius Gieaiid (185H), Pac. E. R. Surv. x, 234. 

 1860 — Plargyrus mclanoceplialus Abbott, Proc. Acad. Nat. Sci. Phila. 325. 



Pimephales melanocephalits Jordan & Copeland (1876), Check List, 146. 

 1864 — Piimpliales milesii Copk, Proc. Acad. Nat. Sci. Phila. 282. , 



Pimephales ynilesii GiJNTHifiR (1868), Cat. Fishes, vii, 181. 



Pimepliales milesii Jordan (1876), Man. Vert. 276. 

 1866 — Pimephales agassizii Cope, Cyp. Penn. 391. 



Pimephales agassizii Jordan (1874), Ind. Geol. Surv. 224. 



Numerous specimens, to all appearance precisely like others from the 

 Ohio Eiver ; the lateral line is imperfect and extends to a little past the 

 beginning of the dorsal. 



Genus COUESIUS Jordan, gen. nov. 



7. — CouESius DissiMiLis (Grd.) Jordan, 



1856 — Leucosomus dissimilis Grd., Proc. Acad. Nat. Sci. Phila. 189. 



Leucosomus dissimilis Girard (1858), U. S. Pac. R. R. Exp. x, 250. 



Semotilus dissimilis Jordan, Bull. U. S. Geol. Surv. Terr. 1878, iv, 427. 

 1877 — Nocomis milneri Jordan, Bull. Nat. Mus. s, 64. 



Ceratichthys milneri Jordan (1878), Bull. U. S. Geol. Surv. Terr, iv, 427. 



Ceraiichthys milneri Jordan (1878), Man. Vert. 2d ed. 307. 



This species was first described by Girard from specimens from the 

 Upper Missouri region, and referred by him to the genus Leucosomus 

 {=8emotilus). Ashe did not describe especially its dentition, it has 

 been presumed by myself and others that the species really was a ISe- 

 motllus, and, if so, probably related to the Eastern Semotilus bullaris 

 [rhotheus Cope), a species without the usual black dorsal spot. 



Specimens collected in Lake Superior by Mr. J. W. Milner were 

 'ateiy described by me as Nocomis { = Ceratichthys). milneri, without a 

 thought as to the necessity of comparing them with one of Girard's 

 Leucosomi. 



Comparison of the numerous specimens collected by Dr. Coues with 

 Grirard's description and my own leaves no doubt whatever in my mind 

 as to their identity both with Leucosomus dissimilis and Ceratichthys mil- 

 neri. The specific name dissimilis, however, cannot be used for this 

 species, if reierred to Ceratichthys, as there is already a " dissimilis " 

 [Leuciscus dissimilis Kirtland) in the genus Ceratichthys. The reprehen- 

 sible custom, so often practised by Girard, of giving, as. specific names 

 to new species, names already borne by species of allied genera, always 

 leads to confusion as the boundaries of genera are changed. If referred 

 to Ceratichthys, then the species should stand as Ceratichthys milneri 

 Jordan. 



Since the above was written, the author has reviewed some of the 

 characters on which our current genera of Cyprinidce rest. I am dis- 

 posed to agree with Professor Cope that the presence or absence of the 

 single tooth forming a second row is not, in most cases at least, a good 



