118 
U. S. P. R. R. EXP. AND SURVEYS-ZOOLOGY—GENERAL REPORT. 
is quite large, its gape being obliquely directed upwards, and the 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, which are small and exiguous, and oftentimes 
obsolete. The vomerine teeth constitute a conspicuous patch. The eye is moderate, suh-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 development; rather short and 
rounded. The rays, as nearly as we could ascertain, number as follows: 
Br. IY : IY ; D LXXXYI-XC ; A I, 40-43 ; C 4, 1, 11, 10, 1, 3 ; Y 0 ;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 uniform greyish yellow throughout. A black filet may be traced from the occi¬ 
pital region to the superior rim of the 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. 
Catal. 
No. 
No. of 
spec. 
Sex and 
age. 
Locality. 
When 
collected. 
Whence obtained. 
Orig. 
No. 
Nature of 
specimens. 
Collected by— 
494 
i 
Adult... 
Presidio, Bay of San Fran¬ 
cisco, California. 
1853 
Lt.W. P.Trowbridge 
Alcoholic .. 
Lt. Trowbridge... 
495 
i 
San Francisco, Cal. 
. 1856 
Dr. W. 0. Ayres.... 
22 
... .do. 
Dr. Ayres. 
2. APODICHTHYS YIRESCENS, Ayres. 
Spec. Char. —Exterior row of inaxillar teeth larger than the internal row. Mouth moderate ; posterior extremity of max¬ 
illar bone extending to a vertical line drawn within the posterior rim of the orbit. Origin of dorsal fin situated in advance of 
the base of the pectorals. Caudal fin moderate. Color, greenish olive, or bright pea green, maculated with black. A black 
filet 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. 
Syn. —Jlpodichthys virescens, Ayres, 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 hy Dr. Ayres to the Smithsonian Institution, and labelled A. 
virescens, one .we referred, without hesitation, to A. flavidus, 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. flavidus. 
The chief differences observed are pointed out in the above diagnosis,- which will bear com- 
