316 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



with 3 rather short spines; ventral thoracic, with 1 spine and 5 soft 

 rays. 



A single genus is represented among the Peruvian collections studied. 

 The species of this family are herbivorous, feeding largely on algae. 

 As usual in herbivorous fishes, the intestinal canal is long. 



Genus DOYDIXODON Valenciennes, 1855 



Body rather deep, moderately compressed ; head short, blunt; mouth 

 small; jaws with an outer band of enlarged movable teeth, arranged in 

 oblique rows meeting on median line of each jaw, each tooth with a 

 narrow basal support and with an expanded bicuspid or tricuspid, or 

 entire edge, generally spoon-shaped, a band of minute teeth behind 

 the outer ones; scales extending more or less on the fins, but not cov- 

 ering any fin entirely; dorsal with 12 or 13 spines and 15 to 18 soft 

 rays. 



A single species is recognized herein. However, when a larger 

 series of specimens, including a wider range in size, becomes available, 

 it may become necessary to recognize two or more species. 



DOYDIXODON LAEVIFRONS (Tschndi) 



Babunco; Gallinazo 

 Figure 68 



Pimelepterus laevifrons Tschudi, 1845, p. 18, Huacho, Peru (original description). 



Doydixodon laevifrons Jordan and Fesler, 1893, p. 532 (original description 

 quoted). — Starks, 1906, p. 792, pi. 66, fig. 2, MoUendo, Peru (this species 

 and D. freminvillei compared; both species illustrated). — Evermann and 

 Radcliffe, 1917, p. 94, Lobos de Afuera and MoUendo, Peru (synonymy; 

 description). — Nichols and Murpht, 1922, p. 509, Chincha and Ballestas 

 Islands, Peru. 



Head 3.2 to 3.6; depth 2.2 to 2.4; D. XII or XIII, 15 or 16; A. Ill, 



12 or 13; P. 18; scales 52 to 55. 



Body deep, moderately robust, its greatest thickness somewhat less 

 than half its depth; back fairly high; profile anteriorly rather strongly 

 convex; head short and deep; caudal peduncle long, 1.75 to 1.85 in 

 head; snout rather blunt, 2.3 to 2.5 in head; eye small, 4.6 to 5.0; 

 interorbital 2.25 to 2.6; mouth small, slightly inferior; upper lip broad; 

 maxillary reaching somewhat beyond front of eye, 2.5 to 2.8 in head; 

 teeth anteriorly in each jaw in 3 or 4 oblique rows, meeting at mid- 

 line of jaw, each tooth with a narrow basal stalk, and expanded dis- 

 tally, more or less spoon-shaped, distally rounded, square or slightly 

 notched, a band of minute teeth in each jaw behind the outer teeth 

 and well separated from them; preopercle entire; opercle ending in a 

 broad flat point; gill rakers about as long as pupil, 18 or 19 on lower 

 and about 12 on the upper limb of first arch; scales with slightly 

 crenulate, membranous edge, reduced anteriorly above lateral line, 



