40 MONOGRAPH OF THE FRESH WATER III. 



one-third of the depth of the body. The second dorsal, twice as long as the first, 

 is separated from the latter by a space less than a line. It contains eighteen 

 articulated and simple rays, with the exception of two central ones which are very 

 slightly forked. The apal is composed of fourteen articulated, but simple, rays ; 

 its origin is opposite to the sixth ray of the second dorsal and terminates, as usual, 

 before the latter. The caudal, one-sixth of the total length, unites with the tail 

 in a straight line; its rays, fifteen in number, are more or less subdivided or else 

 dichotomized. The ventrals, arising a little behind the pectorals, contain five rays. 

 of which four are soft and articulated, and one spiny, slender, and half the length 

 of the others, close to the anterior or outer edge of the fin, and concealed by the 

 skin. The pectorals are large and fan shaped ; the rays of which they are com- 

 posed are all articulated but not branched, the longest equalling the head in length. 



Br. 6. D VIII. 18. A 14. C is. V I. 4. P 15. 



" The under surface is silvery-gray minutely spotted with dark brown : on the 

 sides, the dots are intermingled with crowded, irregular blotches of the same 

 color, and on the back and top of the head the color is dark brown, nearly uni- 

 form, few spots of the light color appearing." (Ricn.) 



Sir John Richardson gives four inches as the total length of this species; we 

 regret not having had the opportunity of studying it in nature ; but there exist 

 no specimens to our knowledge in any public or private collection of fishes in the 

 United States. We regret likewise that the author of the Fauna Bort-a/l-A m> ri<->i,,a 

 has not had it figured ; the more so that it resembles so much its congener of 

 both continents. 



III. COTTUS WILSOXII, GIKAUI>. ^lUwuiU* YltX 

 PLATE I. Figs. 3 and 4. 



In visiting the collection of fishes at the Academy of Natural Sciences of Phila- 

 delphia, in November 1850, we saw aCottus labelled "Pittsburgh (Pa.)," presented 

 by Mr. Jacob Green. After a careful examination of the unique specimen pre- 

 served in that cabinet, we satisfied ourselves that it belonged to a species distinct 

 from any one hitherto known, and took pleasure in dedicating it to Dr. Thomas 

 B. Wilson. Indeed, before that time, we had seen immature specimens of the same 

 species, but we were unable to characterize it until we met with the one just men- 

 tioned. 



The size of the individual figured and described is four inches and a quarter. 

 The head forms exactly the fourth of that length. With regard to the general 

 form it is amongst all the species the one whose depth diminishes least rapidly back- 

 wards. The greatest depth is comprised nearly six times in the length, and the 

 least depth, on the peduncle of the tail, only twelve times. The thickness is a 



but simple, to tbo second, whilst Cuvicr found in the latter seventeen to eighteen ravs, the last of which is 

 branched, and some of the middle ones forked. Tliew facts must be taken into consideration in making a 

 critical revision of the European Cotti. 



