62 U. S. p. R. R. EXP. AND SURVEYS — ZOOLOGY — GENERAL REPORT. 



the " prickly bullhead," some of which collected near Astoria, others above the Cascades, at 

 Fort Dalles. Tlieir average size is between six and seven inches, a few inches smaller than 

 those described by Sir John Richardson. 



The body, viewed in profile, is sub-fusiform, tapering gradually backwards ; it is compressed and 

 deeper than broad throughout the whole length, though the difference in height and depth 

 become greater posteriorly. The dorsal line is slightly arched, whilst the abdominal is 

 nearly straight. The head, which is broader than deep, forms the third of the entire length, 

 the caudal fin excluded. The upper surface is depressed, the cranial region widely concave, 

 without the least trace of ridges, tubercles, or spines, except the minute spines of the turbinal 

 bones which are hidden under the skin. The snout is sub-convex above, and rounded upon its 

 periphery. The jaws are of equal length, though the inferior lip may project somewhat beyond 

 tlie upper when the mouth is closed. The latter is broad ; the posterior extremity of the 

 maxillary extends to a vertical line intersecting the posterior edge of the pupil. The eyes are 

 of medium size, sub-circular or elliptical in shape, contained, by their longest diameter, five 

 times in the length of the side of the head ; the interocular space is about one of their diameter ; 

 the rostral distance is greater of one-fifth or sixth. The anterior nostril is situated nearly mid- 

 ways between the rim of the orbit and the margin of the upper jaw. The convexity of the 

 preopercle is armed with an acute spine, curved upwards and covered by the skin so as scarcely 

 to be seen exteriorly. The inferior edge of the same bony piece exhibits two minor spines 

 entirely buried under the integuments. The inferior angle of the opercle has a similar spine 

 directed forwards. Finally, the scapular terminates into an acute point concealed under the 

 skin and perceptible only to the touch. 



The origin of the first dorsal is situated on a vertical line intersecting the base of the upper 

 ray of the pectorals ; it is composed of nine, sometimes ten, rays implanted upon a base not 

 quite half the length of the second dorsal, to which it is connected by a low membrane ; the 

 sixth and seventh spines are the longest ; the outline of the fin forms a convex, somewhat 

 depressed line. The second dorsal commences a little in advance of the anus, extending also 

 somewhat further back than the anal ; it is composed of twenty-one or two undivided rays, projecting 

 beyond their membrane. The caudal is slightly rounded posteriorly ; it is contained six times 

 and a half in the total length, composed of nine branched rays and a few simple ones. The 

 origin of the anal is situated opposite the fourth ray of the second dorsal ; it is not quite so 

 deep as the latter is high ; seventeen undivided rays may be observed in it. The interradial 

 membrane is more deeply emarginated than in the second dorsal. The ventrals are situated 

 posterior to the three inferior rays of the pectorals, and anterior to the upper ones. The 

 extremities do not reach the anus. The pectorals are broad, obliquely obovate, composed of 

 sixteen or seventeen undivided rays, with the interradial membrane emarginated between all 

 of them, though less deeply between the upper rays, which are also more slender than the 

 lower ones. Their extremity reaches a vertical line intersecting the anterior margin of the anal. 



Br. VI— VI ; D IX, 21 ; A 17 ; C 3, 1, 5, 4, 1, 2 ; V I, 4 ; P 17. 



Br. VI— VI ; D X, 22 ; A 17 ; C 3, 1, 5, 4, 1, 2 ; V I, 4 ; P 16. 



Showing a very slight difference between the rays in specimens of different localities. 



The lateral line is conspicuous, in the shape of a furrow exhibiting a series of contractions. 

 From the upper angle of the thoracic arch it takes its course along the flanks, keeping nearer 

 the dorsal than abdominal outlines, sometimes deflected under the posterior portion of the second 

 dorsal, as in Cotlus proper. 



There are no scales ; the skin of the head is perfectly smooth ; the vertex, however, is provided 



