REPORT ON ICHTHYOLOGY. 401 



appears to be questionable. Dr. Girard, in his monograph of the genus, published 



by the Smithsonian Institution, lms asserted that when young some species of Cottus 

 "exhibit teeth-like asperities on the palatines, 'litis occurs chiefly amongst those having 

 four jointed rays to the ventrals: in C Wilsonii, C, Bairdii, and C. Meridionalis. C. 

 gracilis is the only one of the division with three jointed rays where similar asperities 

 have been noticed." This assertion has not, however, been continued by my investi- 

 gations. An examination of the types of the Cottoids described by Dr. (J hard, in his 

 "Monograph", has demonstrated that the presence or absence of teeth in the palatine 

 bones is constant in the various species. In the Cottus Birhardsonii, C. )V'dsouii, and 

 C. meridionalis, teeth are always found on the palatines, in the oldest as well as the 

 youngest individuals. The Cottus Bairdii cannot be at present found; but the same is 

 doubtless the case with that species. Many other specimens preserved in the Smith- 

 sonian Museum exhibit the same constancy in their dentition. 



As to the Cottus gracilis, it is said by Dr. Ayrcs, in his Memoir on the Identity of 

 the North American Cotti with the Cottus gobio of Europe, that of the very numerous 

 specimens of the Connecticut Cottus (C. gracilis Meckel), which he had examined, he 

 had seen a single one in which there were a few scattered teeth on the palatines, like 

 those of the vomer; in others, those bones were edentulous. It is probable that that 

 instance is alluded to by Dr. Girard in his mention of palatine teeth having been dis- 

 covered in the Cottus gracilis. An isolated fact like that recorded by an observer who 

 has failed to appreciate the distinctive characters of species of this group cannot, 

 however, be urged as a valid objection to the importance of such characters. Nor 

 could the circumstance that some Cotti have teeth when young, which they lose with 

 age, militate againsl assigning a certain value to a plan of dentition which is constant 

 through life, as well in the young and old. The difference of development alone 

 would be a character of importance. But there does not appear to be even such 

 difference between the dentition of the young and old. In those specimens which 

 Dr. Girard described, the dentition is constant. Palatine teeth are even found in indi- 

 viduals which are much larger than any without. Such is the case with the species 

 now under consideration ; such is the case with other species equally large from the 

 Western States. 



If the above views are correct, it would then appear to be advisable to separate 

 the Cotti with palatine teeth, and place them in another genus, or, at least, a subgenus, 

 to which the name of Potamocottus may be given. This group will embrace the Cottus 

 punrttdatus as its type, and, in addition, Cottus meridionalis Girard, C. Bairdii Girard, 

 C. Wilsonii Girard, and C. Bichardsonii of Agassi z, as well as Cottopsis gulosus of 

 Girard. The genus Potamocottus would bear the same relation to Uranidca that Bryttus 

 does to Pomotis, or Scorjuena to Srarjucnopsis of Hoeckel. 



The genera Uranidca, Potamocottus, and Cottopsis agree very closely together, 

 both in superficial and anatomical characters, and differ in the most decided manner 

 from Cottus and the related genera; to express this divergence, the genera in ques- 



