U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY-GENERAL REPORT. 
ASPICOTTUS BISON, Grd. 
Plate XY, Fig. 1. 
Spec. Char. —The posterior extremity of the maxillary extends to a vertical line drawn mi'dway between the posterior 
edge of the pupil and the posterior rim of the orbit. The scutellae constituting the lateral line are crowded, vertically 
elongated. Upper regions dark brown, mottled or blotched with black. Beneath dull yellowish, with meandric dark 
lines under the head and throat. Ventrals uniform yellowish white; other fins mottled yellow and black. 
Syn. —Aspicottus bison, Grd. Proc. Acad. Nat. Sc. Philad. VII, 1854,130 ; &, VIII, 1856,133. 
Clypeocottus robustus, Ayres, Proc. Cal. Acad. Nat. Sc. 1,1854,11. 
The head, which constitutes about the third of the whole length, the caudal fin excluded, is 
very large, and much broader than deep. The body in being likewise broader than deep upon 
its anterior third, the consequence is the short and stoutish appearance of this species. The 
upper surface of the head is corrugated, the orbital region is convex and raised above the general 
surface ; the cranium is slightly depressed between two parieto-occipital ridges. The eyes are 
sub-circular, of moderate developmenttheir longitudinal diameter enters about five times in 
the length of the sides of the head. The posterior nostril is the smallest, and is situated imme¬ 
diately in advance of the orbit and behind the turbinal hone on the upper surface of the snout. 
The anterior nostril opens on the side of the snout exteriorly to the turbinal and nearer the 
orbit than the margin of the jaw; its posterior margin is provided with a fringed membranous 
expansion.’ The snout is declivous and rounded ; the jaws are equal, and the mouth broad 
though not deeply cleft, since the posterior extremity of the maxillary does not extend as far 
back as the posterior rim of the orbit. The middle suborbital is stout and conspicuous, termi¬ 
nating into a flattened point at the concavity of the preopercle. The latter is provided with 
four spines, the uppermost being very long, and extending backwards to the posterior edge of 
the opercle, which it sometimes overlaps ; the two next ones are small and directed obliquely 
downwards ; the fourth may be seen at the lower extremity of that bone and directed obliquely 
forwards. The opercle has three spines—one, rather stout, along the upper margin of that 
bone, and two small ones towards its inferior margin, and directed obliquely downwards. 
Finally, the posterior extremity of the interopercle exhibits the last and smallest spine of the 
opercular apparatus. The isthmus is rather large, being equal to about the third of the dis¬ 
tance between its angle and the extremity of the lower jaw. The branchiostegals are six in 
number, all well developed. 
The origin of the first dorsal corresponds to a vertical line drawn immediately behind the 
upper portion of the insertion of the pectorals, and, consequently, at a very short distance from 
the occiput. It is composed of eight rather slender spines, the fourth and fifth of which being 
the highest; the fin itself is lower than the second dorsal, and its upper outline sub-convex. It 
is separated by a narrow space from the second dorsal, which is composed of twelve rays inserted 
upon a base one-third longer than that of the first. The caudal, which constitutes about the 
sixth of the entire length, is posteriorly sub-truncated, composed of nine bifurcated and two un¬ 
divided rays, with several rudimentary ones above and below. The origin of the anal is situ¬ 
ated opposite the fourth ray of the second dorsal, and does not extend as far back as the latter, 
although the tips of the last rays may be even, owing to the greater length of the posterior rays 
of the anal. The fin itself is not quite so deep as the second dorsal; the membrane between 
the rays is deeply emarginated. The insertion of the ventrals is nearly opposite the middle of 
the base of the pectorals; they are elongated, but do not reach the vent, which is situated a 
