290 
U. S. P. R. R EXP. AND SURVEYS-ZOOLOGY—GENERAL REPORT. 
A large species: the largest hitherto known of this genus. It is twelve inches in total length, 
the head forming somewhat less than the fourth of it. The greatest depth is nearly equal to 
the length of the head. The eye is suh-circular, and its diameter contained about six times, or 
a little more, in the length of the side of the head. The dorsal and anal fins are sub-trapezoid, 
the anal being smaller than the dorsal. The origin of the ventrals is situated hut slightly in 
advance of the dorsal fin. The latter is higher than long : a character of the genus. The pec¬ 
torals and ventrals are of moderate development. 
D 1, 8, or 1, 9 + 1 ; A 2, 8 + 1 ; C 8, 1, 9, 8, 1, 7 ; V 1, 10 ; P 18. 
The scales are quite large, deeper than long upon the anterior portion of the body, and longer 
than deep upon the posterior portion, with numerous radiating grooves upon their posterior 
section only. The lateral line is somewhat deflexed on the middle of the flanks and nearer the 
insertion of the ventrals than the base of the dorsal. 
The dorsal region is bluish grey ; the sides and belly are silvery white, sometimes golden, 
hut always in contrast with the tint of the back. 
List of specimens. 
Catal. 
Cor’g No. 
No. of 
Age. 
Locality. 
When col¬ 
Whence obtained. 
Nature of 
Collected by— 
No. 
of teeth. 
spec. 
lected. 
specimens. 
234 
2788 
3 
A.&Y. 
Klamath lake, Oregon... 
1855 
Lt. R. S. Williamson. 
Alcoholic. 
Dr. J. S. Newberry. 
3. TIGOMA OBESA, Grd. 
Spec. Char. —Body short and compact; peduncle of the tail rather attenuated. Head small, constituting the fifth of the 
total length. Snout abbreviated and rounded ; posterior extremity of maxillar bone extending to a vertical line drawn in front 
of the orbit. Eye moderate sized, sub-circular; its diameter entering a little over four times in the length of the side of the head. 
Anterior margin of dorsal fin nearly equidistant between the extremity of the snout and the fork of the caudal fin. Origin of 
ventrals somewhat nearer the insertion of the caudal than the extremity of the snout. Bluish grey above ; yellowish white 
beneath, with a lateral reddish streak. 
Syn. —Tigoma obesa, Grd. in Proc. Acad. Nat. Sc. Philad. VIII, 1856, 206. 
A very characteristic species, owing to its short and deep body, its short and conical head, and 
its small fins. It hears a general resemblance to T.'purpurea, but its head is much smaller. 
The anal fin is somewhat larger than the dorsal, both of them are sub-trapezoid in shape. The 
extremities of the ventrals are far from reaching the vent: the same is true of the pectorals with 
reference to the origin of the ventrals. The following formula gives the number of the rays : 
El, 8 + 1; A 2, 9 + 1; C 6, 1, 9, 8, 1, 5; V 1, 8; P 15. 
The scales are moderately developed, presenting the same variations in length and depth, 
according to the regions of the body where they occur, as in T. bicolor. The lateral line is 
nearly median, being but slightly deflexed and but slightly nearer the insertion of the ventrals 
than the base of the dorsal. 
The upper region is bluish grey, whilst the inferior region is yellowish white. A reddish 
streak may be observed above the lateral line from the opercular apparatus to the tail. The 
vertical fins are greyish yellow ; the pectorals and ventrals exhibiting a rather more yellowish 
tint. 
