FISHES—C YPRINID AE-LAVINIA EXILICAUDA. 
24] 
1. L AVINI A EXILICAUDA, B. & GL 
Plate LIV, Figs. 1—4. 
Spec. Char. —Body very compressed, quite deep upon its middle ; peduncle of tail rather slender. Head small; eye 
moderate ; posterior extremity of maxillary not reaching the anterior rim of the orbit. Isthmus small. Insertion of ventral 
fins situated in advance of the anterior margin of the dorsal. Pectorals rather small. Caudal deeply furcated. Reddish brown 
above, silvery grey on the sides, the scales being minutely dotted upon their margin. Beneath yellowish. 
Syn. — Lavinia exilicauda, B. & G. in Proc. Acad. Nat. Sc. Philad. VII, 1854, 137.— Grd. in Proc. Acad. Nat. Sc. Philad. 
VIII, 1856, 184. 
Lavinia compressa, Ayres, in Proc. Cal. Acad. Nat. Sc. I, 1855, 21. 
The body is compressed, swollen upon its middle and tapering towards both, extremities. 
The tail is more particularly attenuated. The greatest depth in advance of the dorsal is 
contained about four times in the length, which is eleven inches, and in which the head enters 
five times and a half. The mouth is very small; its angle being far from reaching the anterior 
margin of the orbit. The eye is circular and rather below the medium size; its diameter being 
contained nearly six times in the length of the side of the head. The isthmus is very small; the 
branchiostegal rays are three on either side. The anterior margin of the dorsal is equidistant 
between the extremity of the snout and the tip of the central rays of the caudal, which latter fin is 
deeply furcated. The base of the anal is longer than that of the dorsal but considerably lowers 
particularly upon its posterior third. The insertion of the ventrals is placed in advance of the 
anterior margin of the dorsal. The pectorals are rather small. 
D 2, 12; A 2, 14 or 15 ; 0 7, 1, 8, 8, 1, 7 ; V 1, 10 ; P 17. 
The scales are rounded, somewhat longer than deep, and very thin, with radiating furrows 
upon their posterior section only. The lateral line, in which there are about sixty scales, forms 
an open curve on the abdomen with a downwards convexity jguich nearer the insertion of the 
ventrals than the base of the dorsal fin. L 
The color is reddish brown above, silvery grey on the sides, the scales being provided with 
minute crowded dots upon their margin. Beneath yellowish with the scales unicolor. The 
fins being yellowish grey. 
References to the figures. —Plate LIV, fig. 1, represents Lavinia exilicauda , somewhat reduced 
in size. Fig. 2 is a scale from the dorsal region. Fig. 3, a scale from the lateral line. Fig. 
4, a scale from the abdominal region. 
List of specimens. 
Catal. 
No. 
Cor. No. 
of teeth. 
No. of 
spec. 
Age. 
Locality. 
When col¬ 
lected. 
Whence obtained. 
Nature of 
specimen. 
Collected by— 
207 
2765 
2 
Adult. 
Sacramento river, Cal. 
1853 
Lt. R. S. Williamson.. 
Alcoholic. 
Dr. A. L. Heermann.. 
208 
2 
Young 
Posfi C!al ....... 
1853 
209 
2766 
2 
Adult. 
San Joaquin river, Cal. 
1855 
Dr. Jno. S. Newberry., 
31 a 
