ADDENDA. 



Page 43, before Cottus polaris. 



[126.] 2( bis ) Cottus asper. (Richardson.) Prickly Bull-head. 



I am indebted to Dr. Gairdner for this interesting and very distinct species of 

 fresh-water Bull-head, which is common in the Columbia River. It resembles 

 gobio in its general form, but is distinguished from it, at first sight, by the rough- 

 ness of the skin, exclusive of other characters. It is a larger fish. 



DESCRIPTION 

 Of a male specimen. 



Form. — Head not so much depressed as in gobio, its height being proportionably greater 

 and its breadth less ; it forms a third part of the length of the fish, excluding the caudal. The 

 top of the head is flat, or rather widely concave, the margins of the orbits being smoothly and 

 roundly elevated ; there are no other indications of lateral ridges, nor any tubercles or spines 

 on the top of the skull. On close examination a small spinous point may be detected on the 

 nasal bones ; the operculum ends in a thin flat point, which is masked by a narrow, flexible, 

 cartilaginous process of the suboperculum, imbedded in membrane, and forming the tip of the 

 gill-cover ; the suboperculum ends anteriorly in an acute point, but its edge is even : the spine 

 at the angle of the preoperculum is more evident, and when divested of the skin which envelops 

 it, shows a very acute, clear point, curved slightly upwards ; the under edge of the preoper- 

 culum forms two distinct angular points : the scapular bone ends in an acute point, which can 

 scarcely be felt through the skin, but none of the bones margining the gill-openings, nor any of 

 the opercular pieces, are serrated. In the recent specimen the spines are perceptible only to 

 the touch, being concealed from the eye by the integuments. The posterior tips of the inter- 

 maxillary pedicles may be mistaken for spines. The under Up projects a little beyond the upper 

 one when the mouth is closed. The eyes are more than one of their diameters apart. The 

 Skin of the head is quite smooth to the touch, but it is dotted, particularly on the crown, with 

 minute soft warts. The belly, a stripe adjoining the anal on each side, a small space round 

 the base of the caudal, and the interscapular space anterior to the first dorsal, are also smooth; 

 but the rest of the skin of the body is thickly studded with very small, subulate, acute spines 



