40 



submarginalem monstrans ; fossa cardinal! minime profunda : v. in- 

 ferioris perforatione acuto-ovato ; c'avicula vix dilatata, quasi costa 

 secundum marginem perforationis prolongata. Diam. 25 ; lat. 4 mil- 

 lim. Inhabits Kagosima Bay. W. S. 



It most resembles P. claviculata from Mazatlan. 



Observations ox the genus Cottus, and desckiptions of 



TWO NEW SPECIES (ABRIBGED FROM THE FORTHCOMING RE- 

 PORT OF Capt. J. H. Simpson), by Theodore Gill. 

 The genus Cottus^ as restricted by Doctor Charles Girard, embraces 

 species with and without palatine teeth, but in all other respects 

 similar. If the arrangement of the teeth is in all cases of generic 

 importance, the species of Cotti must then be distributed among two 

 genera. Such genera would bear nearly the same relation to each 

 other as the Brytti of Cuvier do to Pomotis ; as the true Scorpcence 

 do to the genus Scorpcenopsis of Heckel, and as many genera of 

 Clujyeince bear to each other. For our present purposes we may, 

 however, regard the Cotti as forming a single natural genus, all of 

 whose species are very similar in form and structure, but, on account 

 of the difference in dentition, are divisible into subgenera. As the 

 type of the genus Cottus has no palatine teeth, that name must be 

 restricted to species so distinguished ; the Cotti with palatine teeth 

 may then be designated by the name of Potamocottus. In the forth- 

 coming report of Captain Simpson, the characteristics and nomen- 

 clature of the genus will be more fully discussed. It will be sufficient 

 to state here that Dr. Girard's assertion, that, when young, some 

 species of Cottus " exhibit teeth like asperities on the palatines," does 

 not appear to apply to the typical Cotti^ which seem always to have 

 the palatine bones edentulous. The Potamocotti, on the contrary, of 

 all sizes and ages, have teeth on those bones. Even if some of the 

 typical Cotti have, in their youth, teeth which they lose with age, the 

 fact would scarcely militate against assigning a certain value to a 

 plan of dentition which is constant through life. 



The species of Potamocottus now knoAvn are the Cottus Richardsonit 

 of Agassiz, Cottus 7nendionalis of Girard, Cottus Wilso7iii of Girard, and 

 Cottus Bairdii of Girard. 



The two new species of which diagnoses are now given, will be 

 fully described and ilkistrated in the forthcoming Report by Captain 

 J. H. Simpson, of his Explorations across the Continent in the years 

 1858 and 1859. 



Potamocottus punctulatus Gill. 

 This species has a form similar to those which are placed by Dr. 

 Girard in the first division of the first section of his systematic dis- 

 tribution of the Cotti. The head is much depressed, and rhomboidal 



