HTBOGNATHUS.— ALGANSEA. 151 



San Juan in Nuevo Leon * ^ 7 9 {J^lgf.jc'j ; Durango in Durango ^ ; Rio Verde in 

 San Luis Potosi 11 12 ^Me£Jc). 



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 Hyhognathus 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 Si)ecies. 



I. 10 to 12 gill-rakers on the lower part oE the anterior arch; G7 to 7Q scales in a longitudinal 



series. 



12 to 14 scales between lateral line and base of ventral fin 1. tincella. 



8 to 11 scales between lateral line and base of ventral fin ........ 2. afjinis. 



II. 13 or 14 gill-rakers on the lower part of the anterior arch ; GO 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)' ; GLinth. Cat. Fish. vii. 



p. 244 {1868)\ 

 Algansea tincella, Girard, U.S. & Mex. Bound. Surv., Fish. p. 46, t. 27. figs. 1-4 (1859)'; Jord. 



Ss 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 3| to 4i ia the length, length of head 3| to 4. Snout considerably longer than eye, the 

 diameter of which is 5^ 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 i to | the length of head. Anal 8, with 

 6 branched rays, when laid back not reaching the caudal fin. Pectoral f to 4- the length of head, not 

 extending to the ventrals, which are inserted nearly below the origin of dorsal. Silvery ; back brownish ; 

 fins pale. 



Hah. Valley of Mexico ^ ■ 



35 



Here described from four specimens, 100 to 150 mm. in total length, from Mexico 

 {Mexico Mus.) and Chalco {Meek). 



2. Algansea affinis, sp. n. (Tab. XXV. fig. l.) 



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 4| in the length of the fish. Snout longer 



