1856.] 183 



There is a narrow isthmus between the gill openings. The body short and 

 stoiitish, quite compressed, covered with scales of medium or of large size, the 

 lateral line being submedial, slightly deflexed upon the middle of the abdomen. 

 The fins are rather moderate in development ; the origin of the ventrals is situ- 

 ated opposite to the anterior margin of the dorsal, the posterior margin of the 

 latter never reaching the anterior margin of the anal. The caudal fin is emar- 

 ginated posteriorly. The pharyngeal bones are moderately strong ; the upper 

 and lower branches of nearly equal strength, though the lower is a little longer 

 than the upper. The convexity is strongly marked and dilated. The teeth are 

 of the cultriform kind of the grinding type, disposed upon a single row of four 

 or five, as follows : 4 4 or 5 5. The uppermost stand boldly out above the 

 surface of the bone. 



1. Algansea tincella. Leuciscus tincella, Y at., in Cuv. & FaL Hist. Nat. des 

 Poiss. xvii. 1854, 323. The scales in this species are next in size to those 

 of ^. obesa. There are about twelve rows beneath and fourteen above the late- 

 ral line. I say about, because the specimens are somewhat mutilated, as most 

 marlvet specimens are. The insertion of the ventrals are situated a little poste- 

 riorly to the anterior margin of the dorsal. The eye is smaller than in any of 

 the preceding species of this genus. Reddish brown above, silvery on the sides, 

 and white beneath. 



Purchased in the city of Mexico by Major Wm. Pdch. 



2. Algansea bicolor. Of all the species hitherto known of this genus, the 

 one here referred to has the largest scales, five rows of which may be counted 

 from the origin of the ventrals to the lateral line, and nine from the lateral line 

 to the anterior margin of the dorsal, in all fifteen rows. The ventrals are in- 

 serted a little in advance of the anterior margin of the dorsal. The body is thick- 

 est auteriorl)-, and tapers backwards ; the nape is slightly swollen. The head 

 enters about four times and a half in the total length. The back and sides are 

 of a metallic bluish black, intermingled on the lower half of the flank with a 

 golden hue. The inferior surface is white, contrasting with the color of the 

 back. 



Caught in Klamath Lake, 0. T., by Dr. John S. Newberry, under Lieut. R. S. 

 Williamson. 



3. Algansea obesa. A very corpulent species covered with scales of mode- 

 rate development, and so far, the smallest in the genus. The depth is contained 

 about three times in the length, caudal fin excluded. There are eight longitu- 

 dinal rows of scales between the origin of the ventrals and the lateral line, and 

 fourteen rows above it to the anterior margin of the dorsal, in all twenty-three 

 rows. Dorsal region bluish grey ; sides greyish ; belly yellowish. 



Specimens of this species were collected in the waters of Humboldt River by 

 the late J. Soule Bowman and Lieut. E. G. Beckwith. 



4. Algansea Formosa. A very graceful and well proportioned fish as regards 

 body and head. The latter is rather slender and conical, constituting the fourth 

 of the total length, in which the greatest depth enters nearly five times. The 

 origin of the ventrals is situated under the anterior margin of the dorsal, as in 

 A. obesa. The scales are next in size to those of A. bicolor. Seven rows are 

 found between the origin of the ventrals and the lateral line, and ten above it, 

 making eighteen rows in all. Metallic greenish brown above and on the sides, 

 minutely dotted with black ; beneath yellowish or whitish. 



This species was collected in Mercede and Mohave rivers, by Dr. A. L. Heer- 

 manu, under Lieut. R. S. Williamson, and is very closely allied to Lavinia gib- 

 bosa, Ayres, but since I have no specimens of the latter, and that those before 

 me measure but five inches and a half, I feel reluctant to attempt an identifica- 

 tion. 



Of all the genera recently established by Prof. Agassiz, there is none 

 that has given me so much difficulty to understand, as his genus Acrocheilus. 



