III. COTTOIDS OF NORTH AMERICA. 43 



little less than the depth. The head is much flattened above, gradually slop- 

 ing towards the end of the snout. Its width is equal to the space comprised 

 between the end of the snout and the base of the preopercular spine. The mouth 

 is very broad; its angles, however, do not extend beyond the pupil. The palatine 

 asperities are more conspicuous than in any of the other species which exhibit 

 traces of them. They occupy an oblong and elongated area on the surface of their 

 bones. The eyes are proportionally small ; their diameter is contained nearly six 

 times in the length of the head. The interorbito-frontal space measures a quarter 

 of an inch, and accordingly, is broader than in any other species. The anterior 

 and posterior nostrils are both tubular. The posterior one, the largest, is situated 

 above in advance of the orbit; the anterior one is nearer the orbit than the end of 

 the snout. The preopercular spine, directed obliquely upwards, is short, stout at 

 its base and very acute at the tip. Underneath, and directed downwards, there 

 exists a second very minute, blunt spine. The isthmus is five-sixteenths of an inch 

 wide. 



The surface of the head exhibits numerous holes all along the tracks of the 

 cephalic channels of the lateral line, by means of which a direct communication is 

 established with the surrounding medium. Several of these holes exist on the 

 snout in the vicinity of the nostrils. They appear more distinct on the specimen 

 figured, on account of the decomposed state of the epidermis which is deprived of 

 all its pigmentum. 



The origin of the first dorsal is one inch and a quarter from the extremity of 

 the snout. Its rays, seven in number, occupy a longitudinal space of five-eighths 

 of an inch, the last ray sending its membrane to the very base of the first ray of 

 the second dorsal. The latter is composed of sixteen rays, the central ones exhibit- 

 ing a slight bifurcation on their summit, without, however, solution of continuity. 

 It extends on a basis of one inch and a quarter, that is, exactly twice the length of 

 the first dorsal. Its anterior edge is nearly of the same height with the middle, 

 and its decrease takes place gradually towards the posterior edge, distant from the 

 caudal three-sixteenths of an inch. The origin of the anal fin is opposite the 

 third ray of the second dorsal. It contains thirteen unbranched rays. The ex- 

 terior margin of this fin is convex, the middle rays being a little longer than those 

 of the second dorsal. The central rays of the caudal are twice subdivided; the 

 posterior margin of this fin is subtruncated ; differing in this respect from that of 

 C. Bairdii. The insertion of the ventral fins takes place, as usual, under the 

 pectorals; but in this species it is considerably more in advance of the first dorsal 

 fin, whilst in C. Bairdii, it is situated immediately under the first ray of the 

 anterior dorsal. They are composed of four soft, jointed, but unbranched rays, the 

 second and third being the longest. The spiny ray is very slender. When bent 

 backwards, the tip of these fins is far from reaching the vent, thus proportionally 

 shorter than those of C. Bairdii. Their more advanced position is not sufficient 

 to account for the difference. The pectorals are broad, with a crescentic base of 

 insertion ; they are composed of fourteen rays, the four uppermost but two, are 

 bifurcated, a character quite peculiar to this species amongst the American ones. 



