152 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 
1 -niicli compressed, laucet-sliaiied, erect, nearly straight. Uiiper limb 
of the pharyngeal bone very broad and concave, separated by a deep 
notch from the dentigerous portion, the bone thin and brittle. Intes- 
tinal canal elongate, about 7 times the length of the lish; i)eritoneiim 
black. Scales small. Lateral line present. Dorsal tin opposite veu- 
trals. Basal rays of caudal largely developed. Anal basis short. 
Pseudobranchijc none. Gill-rakers moderate, clavate, the inner edge 
fringed. Size large. This genus is related to Chonclrostoma, differing 
chiefly in the absence of pseudobranchiie and of the horny mandibular 
I)late. straight ; dowi/, tooth.) 
175. O. micro!ei>i(lotBts (Ayres) Grd. 
Body elongate. Head moderate ; the snout very broad ; eye small, 
about half the length of the snout. Mouth terminal, somewhat oblique, 
broad, the maxillary not extending to the eye. Ui)per head of surfiice 
flattish, with two bony ridges. Fins rather large ; the caudal strong. 
Coloration plain. Lateral line decurved. Head 4; depth 44. D. 0; 
A. 8 ; scales 21-105-12 ; Vert. 24 -f 20. Teeth (3-0 or 0-5, formed much 
as in Camjyostoma, but longer. Size large. L. 12 inches. Bivers of 
California; Great Basin of Utah {Yarroic). 
(Gila microlepklota Ayres, Proc. Cal. Acad. Nat. Sci. i, '21, 1855; Gii’ard, U. S. Pac. 
R. R. Snrv. Fish. 237, lig. ; Guuthcr, vii, 275.) 
74.— I. AVIDIA Girard. 
(Girard, Proc. Acad. Nat. Sci. Phila. 1854, 137 : type Laviiiia exilicauda B. & G. ) 
Body elliptical, elevated, moderately compressed, rapidly contracted 
to the slender caudal peduncle. Head small, conical. Mouth mod- 
erate, terminal, oblique; the lower jaw included. Scales moderate, 
not closely imbricated, the exposed surfaces somewhat hexagonal. 
Lateral line decurved, complete. Belly behind ventrals entirely scaled. 
Dorsal tin well behind ventrals, its last ray just in front of the begin- 
ning of the anal, which is rather elongate. Caudal tin little forked, its 
rudimentary basal rays much increased in number and veiy strong. 
Intestinal canal elongate, 3 times the total length of the flsh; pe- 
ritoneum dark. Teeth 4-5 or 5-5, scarcely hooked, cultriform, with 
rather broad but shallow grinding surface, the largest standing up 
well above the surface of the bone. Gill-rakers rather long and slen- 
der; pseudobranchiie large. Size large. (Larin ia, a classical name, 
without special api)licatiou to these fishes.) 
