112 
BULLETIN OF THE UNITED STATES FISH COMMISSION. 
Leucisciis aud Ricliardsonius. The genus Richardsonius was jiroposed by Girard in 1856. It 
was said to bear some reseuildaiice to SqnaUus, from which it could ‘‘ be distinguished bv the 
smooth edge of the dental ridge and the long ,'iual, together with the peculiar position of the 
latter in reference to the dorsal. The dorsal is also much deeper than long, which is not the 
the case in Sqi(alii(s.’’ Species discovered since Girard’s description was written have shown 
that no such differences between SqnaUus {Leucisciis) and Richardsonius exist. Dr. Gunther 
classed the only two species of the genus Richardsonius with his Abrainis, characterized by the 
elongate anal and compressed ventral ridge behind the ventrals. Jordan and Gilbert also 
separated the genus Richardsonius Ifom I^euciscus, etc., on the basis of the compressed ventral 
ridge and elongate anal. 1 have examined a very large series of specimens and find that the 
ventral ridge is very variable, especially with age, and is of no worth whatever to separate 
Richardsonius even subgenerically from Leuciscus. In one specimen, which might have served 
Girard’s artist when he drew R. haJfeatus, there is the merest vestige of a A-entral ridge. The 
ridge seems best developeil in specimens about medium size (75 mm.). The characters selected 
to separate the species of the old geuus Richardsonius fvoin each other seem no more fortunate. 
Neither the teeth nor the scales are of any value whatever in this respect. The anal fin is by 
no means an absolute guide, as will he seen later. In fact, I have Iteen unable to detect a 
single character Avhich will always separate the two forms, each of which is variable in the 
extreme. All those species of Leuciscus with increased number of anal rays, montanus, hydro- 
jihlox, gilli, halteatus, and lateralis may bo classed mrder the subgeneric name Richardsonius. 
1 find in examining 41 specimens of Leuciscus monUrnus, collected by Jordan at Provo, that 
in some the ventral ridge is much more developed than in tj’^pical specimens of Richardsonius. 
The anal rays are; 28 with 124; 12 with 134; 1 with 14^. 
34 . Leuciscus atrarius (Girard). This species is quite abundant in the Snake River at Idaho Falls. 
It readily takes the hook. The lateral line is not developed until late in life; in specimens 
2 inches long the pores are formed on but few scales. 
35 . Leuciscus hydrophlox (Cope). Abundant in the Snake River at Idaho Falls. The anal rays in 
a number of specimens examined vary from 124 to 14U Two specimens have 12^ rays, 
fourteen have 13^, and four have 14^. The dorsal rays vary from 104 to II 4 , aud the scales of 
the lateral line from 51 to 58. There is present a slight median keel behind the ventrals. 
These specimens agree very closely with specimens of L. montanus collected by Jordan at 
Provo, Utah, except that a larger percentage have 13 and 14 anal rays, aud a smaller percent- 
age have 12 rays. 
36 . Leuciscus balteatus (Richardson). 
Cnnrinus (Ahramis) halteatus Richardson, Fauna Bor. Amer.. iii, 301, 1836; Storer, Svuoiisis Fish. 
, N. A., 160, 1846. 
Richardsonius halteatus Gh'uriX, Proc. Acad. Nat. Sci. Phila., viii, 1856, 202; id., U. S. P. R. R. Exp. 
& Surveys, X, 278, jd. lx, figs. 1-4, 1859 (Fort Dalles, Oreg., Fort Vancouver, Oreg. ?); Bean, 
Proc. U. S. Nat. Mus. 1882,93 (Garrison Creek, Wash.); .Jordan & Gilbert, Syu. Fish. N. A., 
251, 1882 (Columbia River aud northward); Jordan, Cat. Fish. N. A., 33, 1885. 
Ahramis (Blicca) halteatus Giinther, Cat. Fish. Brit. Mus., vii, 309, 1868. 
Of this species I obtained two unquestionable sp)ecimeiis at Kamloojis. There is a distinct 
median ridge behind the ventrals, and the anal has 204 and 224 (ii, 18-^20-^) rays. Teeth, 2, 
5-4, 2. At Mission this species is al)undaut, the largest individuals measuring 140 mm. In 
the larger specimens the postventral keel is very variable and frequently not at all distin- 
guishable;. it is best developed in medium-sized specimens (80 mm.). The teeth are usually 
2, 5-4, 2, when normally developed. Of these, the anterior tooth on the left is thicker and 
shorter than the others, dagger-shaped, and remote from them. I have made detailed counts 
and measurements of over 20 specimens, and have counted the rays of all the rest. The anal 
rays are as follows: 164 in two specimens; 17^ in seven; 184 in thirteen; 194 in twenty-five; 
204 in eighteen; 21.^ in eight; 224 in two; 234 in two; 244 in two. The usual number, then, is 
194 or 204. The dorsal varies from 114-134. I have found no coordination of variations what- 
ever. Each character varies independently. The scales vary from 11 to 13-53 to 63-5 to 7. 
According to the Mission specimens the normal number of anal rays is 194- or 204, ^md the 
variation is three or four rays in both directions. 
