188 
U. S P. R, R. EXP. AND SURVEYS—ZOOLOGY-GENERAL REPORT. 
List of specimens. 
Catal. 
No. 
No. of 
spec. 
Sex and 
age. 
Locality. 
When col¬ 
lected. 
Whence obtained. 
Nature of 
specimens. 
Collected by— 
554 
i 
Adult.. 
California__ 
1853 
Lt. W. P. Trowbridge. 
Alcoholic. 
Lt. Trowbridge. 
RHACOCHILUS, Agass. 
Gen. Char. —Head of medium size. Mouth moderate, nearly horizontal, with both jaws equal. Lips very fleshy, lower one 
broad, lobed, and free all around. Premaxillaries very protractile. Teeth few, on the anterior portion of the jaws only, and 
disposed upon one single row. Spinous portion of dorsal fin lower than the soft. Anterior articulated rays of anal fin simple 
and preceded by three small spines. Caudal deeply forked. Scales rather well developed ; lateral line concurrent with the 
dorsal outline. No scales upon the fins. Dorsal groove occupying the middle of the fin ; sheath formed by two rows of scales. 
Syn. — Rhacochilus, Agass. in Amer. Journ. of Sc. 2d series, XVII, 1854, 367. 
As the name implies, the lower lip, which is free all around, is fringed or rather cut up upon 
its margin. The genus is allied to Embiotoca by its dentition and the outline of the dorsal fin, 
differing principally from it by the lower lip not being attached to the symphysis of the jaw, 
and by the indentations of its margin. The protractility of the snout is much greater also than 
in Embiotoca , but not more so than in Holconotus. Like Embiotoca , however, this genus exhibits 
a patch of large scales, isolated amongst the rest, towards the lower portion of the abdomen, 
though placed further back. 
RHACOCHILUS TOXOTES, Agass. 
Plate XL. 
Spec. Char. —General form of body sub-elliptical in profile ; nape prominent, frontal line very declivous. Eye large and 
circular. Posterior extremity of maxillary extending to a vertical line drawn inwardly of the anterior rim of the orbit. Base 
of anal fin (spinous rays excepted) nearly equal to the base of soft portion of the dorsal. Color, uniform olive above ; sides 
silvery with light longitudinal streaks. Pectorals, dorsal, and caudal dark greyish olive ; anal and ventrals dark purple. 
Syn. — Rhacochilus toxotes, Agass. in Amer. Journ. of Sc. 2d. ser. XVII, 1854, 367.—Grd. in Proc. Acad. Nat. Sc. 
Philad. VIII, 1856, 136. 9 
The general form of the body is sub-elliptical in profile, the nape being prominent and the 
frontal line very declivous, with an occipital depression. The outline of the back, as well as 
that of the belly, is regular and rather sub-depressed; along the insertion of the anal the outline 
is rather straight and ascending. The peduncle of the tail is thickish. 
The head is of but moderate development, it being contained four times and a half in the 
total length ; it is a little deeper than long upon the line of its greatest depth, which is the 
occipito-hyoid. The eye is large and circular, its horizontal diameter being contained about 
four times in the length of the side of the head, and more than once in advance of its anterior 
margin. The snout is very protractile downwards, and when retracted it is rounded or sub¬ 
truncated, terminated by very thick and fleshy lips ; the inferior one being free all around and 
presenting three indentations upon its margin: a median, opposite the symphysis of the jaw, 
and two somewhat smaller, lateral, one on each side. The teeth are buried in the thickness of 
