66 U. S. p. R. R. EXP. AND SURVEYS ZOOLOGY GENERAL REPORT. 



ASPICOTTUS BISON, Grd. 

 Plate XV, Fig. 1. 



Spec. Chab. — ^The posterior extremity of the maxillary extends to a vertical line drawn midway between the posterior 

 edge of the pupil and the posterior rim of the orbit. The Bcutellae 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 liead and throat. Ventrals uniform yellowish white ; other fins mottled yellow and black. 



fiyji.—AtpicoUus hUon, Gbd. Proc. Aoad. Nat. Sc. Philad. VII, 1854, 130 ; &, VIII, 1856, 133. 

 Cli/peocnilia rolmitus, Ayre.'*, 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 mucli 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 

 n])per 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 development ,; their 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 bone 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 mCmbranous 

 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 on(!-thir(l 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 cf the pectorals ; they are elongated, but do not reach the vent, which is situated a 



