46 MONOGRAPH OF TIIE FRESH WATER III. 



The top of the head and back are very dark, the sides and belly lighter, yellowish 

 without the large spots. The dorsals, pectorals, and caudal fin are banded; the 

 ventrals and anal, unicolor and only dotted. 



This species may be readily distinguished from C. RicJiardaonii by the shape of 

 the first dorsal, the length of the pectorals, their vertical base of insertion, and the 

 convexity of the posterior margin of the caudal. 



Caught by Prof. Baird in the Mahoning River at Poland (Ohio). Specimens 

 are preserved at the Smithsonian Institution and in Prof. Agassiz's cabinet. 



V. COTTUS ALYOKD1I, GIRARD. - 

 PLATE I. Figs. 7 and 8. 



We have before us the smallest species hitherto described of the genus, mea- 

 suring not quite two inches and a half. Whether it docs not attain a larger size, 

 we are not prepared to decide, as the specimen figured is the only one which we 

 have hitherto seen. But that it belongs to a distinct species is readily apparent. 

 The general form of the body resembles that of C. nv-ridimmlix, tapering suddenly 

 away towards the tail, but the fins differ widely. The head forms a little more than 

 the fourth of the entire length. The greatest depth of the body is contained about 

 five times in the length, whilst the least depth enters in it nearly thirteen times. 

 It is deeper than thick. The anterior region of the body is arched. The neck is 

 depressed and the snout short and obtuse. The mouth is .small; its angle extend- 

 ing not quite as far back as the pupil. The preopercular spine is short and stout, 

 very much curved upwards, and slightly inwards. Below the convexity of the 

 preopercular, there exists another very minute spine, the point of which is directed 

 obliquely downwards. The gill openings are separated below by an isthmus of 

 two-twelfths of an inch. The eyes are proportionally large, subcircular; their 

 longitudinal diameter is contained four times in the length of the head. The ante- 

 rior nostrils are nearer the orbit than the end of the snout. 



The origin of the first dorsal is situated six-eighths of an inch from the extre- 

 mity of the snout. It is composed of seven rays extending on a longitudinal basis 

 of five-sixteenths of an inch. Its upper margin is regularly convex ; the third 

 and fourth rays are the longest; the lir-t ami second have the si/.c of the fifth and 

 sixth ; the seventh is the shortest. The membrane runs from its tip to the 

 anterior margin of the second dorsal, meeting the first ray on the middle of its 

 height. IIow different this fin is from the similar one in C. meridional!.*, an in- 

 spection of both figures will show at once. 



The second dorsal is very close to the first, composed of sixteen undivided rays. 

 the last of which is double. Its upper margin is likewise convex. The origin 

 of the anal is under the third ray of the second dorsal; its outer margin is much 

 more convex than that of the latter, and contains thirteen rays, the last one double. 

 The caudal fin is rounded posteriorly. It is contained six times in the entire 

 length. There are ten fully developed rays, eight of them bifurcated to a con- 

 siderable length. The ventrals are \ery short and broad, inserted immediately 

 er the middle of the pectorals, in advance of the first dorsal. The pectorals 



