HYBOGNATHUS.—ALGANSEA, 151 
San Juan in Nuevo Leon *°‘9® (Meek); Durango in Durango; Rio Verde in 
San Luis Potosi !! * (Meek). 
Here described from several specimens, measuring up to 70 mm. in total length. 
8. ALGANSEA, Girard, 1856. 
Algansea, Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 211. 
This genus differs from Hybognathus in the larger and more oblique mouth and in 
the smaller scales. It comprises four species from the Rio Lerma System (including 
the Valley of Mexico and the upper tributaries of the Panuco). 
Synopsis of the Species. 
I. 10 to 12 gill-rakers on the lower part of the anterior arch; 67 to 76 scales in a longitudinal 
series, 
12 to 14 scales between lateral line and base of ventral fin . . . . . . . . J. tincella. 
8 to 11 scales between lateral line and base of ventral fin . ....... 22 affinis. 
II. 13 or 14 gill-rakers on the lower part of the anterior arch ; 60 to 66 scales 
in a longitudinal series, 7 or 8 between lateral line and base of ventral fin. 3. stigmatura. 
III. 15 to 17 gill-rakers on the lower part of the anterior arch; 76 to 86 scales 
in a longitudinal series. | - 4. dugesi. 
1, Algansea tincella. 
Leuciscus tincella, Cuv. & Val. Hist. Nat. Poiss. xvii. p. 323 (1844)'; Giinth. Cat. Fish. vii. 
p. 244 (1868)°. 
Algansea tincella, Girard, U.S. & Mex. Bound. Surv., Fish. p. 46, t. 27. figs. 1-4 (1859); Jord. 
& Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 45°. 
Algansea tincella (part.), Meek, Publ. Columbian Mus., Zool. v. 1904, p. 44°. 
Depth of body 34 to 4} in the length, length of head 33 to 4. Snout considerably longer than eye, the 
diameter of which is 53 to 7 in the length of head; interorbital width 2% to 3 in the length of head. 
10 to 12 gill-rakers on the lower part of the anterior arch. 70 to 76 scales in a longitudinal series, 
14 to 16 in a transverse series from dorsal fin to lateral line, 12 to 14 between lateral line and base of 
ventral fin. Dorsal 9, with 7 branched rays; origin a little nearer to base of caudal than to tip of 
snout ; free edge straight or slightly convex; longest ray 4 to ? the length of head. Anal 8, with 
6 branched rays, when laid back not reaching the caudal fin. Pectoral 2 to + the length of head, not 
extending to the ventrals, which are inserted nearly below the origin of dorsal. Silvery ; back brownish ; 
fins pale. 
Hab. Valley of Mexico! 3°. 
Here described from four specimens, 100 to 150 mm. in total length, from Mexico 
(Mexico Mus.) and Chalco (Meek). 
9. Algansea affinis, sp.n. (Tab. XXV. fig. 1.) 
Algansea tincella (part.), Meek, Publ. Columbian Mus., Zool. v. 1904, p. 44’. 
Depth of body nearly equal to the length of head, which is 4 to 43 in the length of the fish. Snout longer 
