III. COTTOIDS OF NORTH AMERICA. 49 



4. SPECIES WITH THREE SOFT RAYS TO THE VENTEALS. 



VII. COTTITS GRACILIS, HECK. =- 

 PLATE I. Figs. 11 and 12. 



Syu. Cotlus yracilis, HECK. Ann. d. Wien. Mus. II., 1837, p. 148. GIRARD, Proc. Amer. Ass. Adv. 



Sc. II., 1850, p. 411; and, Proc. Bost. Soc. Nat. Hist., III., 1850, p. 189. 

 Uranidea quiescent, DEKAY, New York Fauna, 1842, p. 61, PI. V. Fig. 14. 

 Coitus gobio, AYRES, Bost. Journ. Nat. Hist., V., 1845, p. 121, PI. XI. 



The history of this species is quite interesting : described abroad for the first time 

 as the second species of Cottus, peculiar to this country, its description remained 

 unknown for years on this side of the Atlantic, and when Dr. Dekay published 

 the Fauna of the State of New York, he even lost sight of the fresh-water Cotti, 

 and proposed for it a new genus. Next we find Mr. Ayres restoring this species to 

 its true genus, and yet misled on the question of the species, an error which he 

 would not have committed if the paper of Mr. Heckel had been at his command. 



This is one of the small species of the genus, scarcely exceeding three inches in 

 length. The specimens which we have had under examination had not quite that 

 size. The general appearance is fusiform, slender, less so, however, than C. boleoides; 

 but on the other hand, it is shorter than the latter, resembling more in shape C. 

 Bairdii. The greatest depth of the body is contained a little more than six times 

 in the total length ; a little less thick than deep anteriorly, it diminishes gradually 

 towards the tail, though more rapidly in thickness than in depth. The latter, on 

 the peduncle of the tail is reduced to the proportions of one-thirteenth of the total 

 length. 



The head forms about the fourth of the total length. The occipital region is 

 slightly sloping backwards, thus giving to the neck a depressed appearance. From 

 the orbits to the end of the snout, the head is rather rounded, although not 

 abruptly truncated. The eyes, circular in form, are one-sixteenth of an inch in 

 diameter, which is comprised nearly four times in the length of the head. Their 

 frontal distance is only the half of their diameter. The anterior nostrils are situated 

 midway between the orbits and the snout ; the posterior ones are higher up, and 

 close to the eyes. The mouth is proportionally great; its angles nearly reach the 

 pupil. The lips are well developed, but the teeth are not very conspicuous. Pala- 

 tine teeth have been assigned to this species, but are not to be found in the specimen 

 figured. There is nothing which resembles teeth on the tongue as ascribed to 

 Uranidea quiescens. The preopercular spine is but little prominent; that of the 

 subopercular is constantly concealed under the skin. The gill openings are oblique; 

 the isthmus is a quarter of an inch wide. There are constantly six branchiostegal 

 rays, even in the specimens in which Dr. Dekay signalizes seven. 



The origin of the first dorsal is six-eighths of an inch distant from the extremity 



of the snout; it is not quite half an inch long, and its height is less than the half 



of its length. Its upper edge is rounded and convex ; the first and second rays 



being a little shorter than the third and fourth; there are eight rays in all; the 



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