118 



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



is quite large, its gape being obliquely directed upwards, and tbe posterior extremity of the 

 maxillary extending to a vertical line drawn behind the orbit. The external row of teeth are 

 large in proportion to those of the inner row, wliich are small and exiguous, and oftentimes 

 obsolete. The vomerine teeth constitute a conspicuous patch. The eye is moderate, sub-circular; 

 its diameter entering about seven times in the length of the side of the head. The branchios- 

 tegal rays are well developed, flattened, and enclosed in a tough membrane ; posteriorly even. 

 There is no isthmus. 



The origin of the dorsal fin is situated opposite the base of the pectorals, hence not far from 

 the occiput, and extends all along the back to the caudal fin, to which it is united. It is quite 

 low, though composed of stoutest spines. The depth of the anal is nearly equal to the height 

 of the dorsal, and likewise united to the caudal. It is composed of articulated and bifurcated 

 rays preceded anteriorly by a stylet-shaped bone much resembling a slender metallic pen, the 

 insertion of which is situated a little nearer the extremity of the caudal fin than the base of the 

 pectorals. The caudal itself is small and rounded upon its periphery, entering about eighteen 

 times in the total length. The pectorals are moderate in develojiment ; rather short and 

 rounded. The rays, as nearly as we could ascertain, number as follows : 



Br. IV : IV ; D LXXXVI-XC ; A I, 40-43 ; C 4, 1, 11, 10, 1, 3 ; V ;P 17. 



The scales are exceedingly small, posteriorly pectinated, and without any lateral line appar- 

 ently. The head, cheeks, and opercular apparatus, are scaleless. 



The color is imiform greyish yellow throughout. A black filet may be traced from the occi- 

 pital region to the superior rim of tlie orbit ; also, from the inferior rim of the orbit obliquely, 

 backwards and downwards, as far as the extremity of the maxillar bone. 



List of specimens. 



2. APODICHTHYS VIRESCENS, Ayres. 



Spec. Char. — Exterior row of maxillar teeth larger than the internal row. Mouth moderate ; posterior extremity of max- 

 illar bone extending to a vertical lino drawn within the posterior rim of the orbit. Origin of dorsal fm situated in advance of 

 the base of the pectorals. Caudal fin moderate. Color, greenish olive, or bright pea green, maculated with black. A black 

 filct from the occiput to the upper edge of the eye, and from beneath the eye obliquely backwards and downwards to the angle 

 of the mouth. 



Stn. — ^poiichlhya vWtictns, Atres, in Proc. Cal. Acad. Nat. Sc. I, 1855, 55. 



We are not altogether satisfied of the specific difference between this and the foregoing species. 

 Out of three specimens sent by Dr. Ayres to the Smithsonian Institution, and labelled A. 

 virescens, one we referred, without hesitation, to A. Jlavidus, though similar in coloring to the 

 remaining two specimens which we record here under the appellation of A. virescens. Their 

 length is from ten to eleven inches, just such as was desirable for comparison with our specimen 

 of A. Jlavidus. 



The chief differences observed are pointed out in the above diagnosis, which will bear com- 



