254 BULLETIN 189, UNITED STATES NATIONAL MUSEUM 



namely, the length of the snout and width of the preorbital, vary so 

 much with age that they are not usable unless specimens more or less 

 equal in size are available. Generally, the species may be separated 

 by the shorter and more slender second anal spine in the present 

 species, the spines being definitely graduated, the second one being 

 notably shorter than the third. However, the length and thickness 

 of the second anal spine vary so greatly fn B. leuciscus that a few of 

 the numerous specimens of that species now at hand cannot be sepa- 

 rated by that character alone. More constant characters are the 

 larger scales on the opercle and cheek in the fish herein called B. 

 nitidus, as shown in the key to the species and in the description. 



It is not certain that the name nitidus is available for this species, 

 because Steindachner's figure, published with the original description, 

 shows too many rows of scales on the opercle and cheek, agreeing 

 in that respect with leuciscus. No mention of the scales on the opercle 

 and cheeks is made in the description. Perhaps the illustrator did not 

 represent the number of rows correctly. The relative size of the anal 

 spines, the length of the snout, and the width of the preorbital ap- 

 parently are correctly shown, as well as described (though the length 

 of the single specimen studied is not stated), for the species herein 

 called nitidus. It apparently will be necessary to examine the type 

 to determine definitely whether B. nitidus (Steindachner) is this 

 species, or B. leuciscus (Giinther). 



Range.— GuU of California to northern Peru. Not abundant any- 

 where so far as known. 



BRACHYDEUTERUS LEUCISCUS (Gttnther) 



Roncador; Roncador db agua dulce 



Pristipoma leuciscus Gunther, 1864b, p. 147, San Jos6, Nicaragua, and "Chiapam" 

 (original description); 1869, p. 416, pi. 66, fig. 3, San Jos6, Guatemala, 

 "Chiapam," and Panama City (description). — Steindachner, 1879b, pp. 30, 

 52, pi. 9, fig. 2, Tumbes, Peru (three examples from Tumbes described and 

 compared with others from Panama, etc. : two from Tumbes described as 

 very slender, one of these illustrated and labeled on p. 52, "Pristipoma 

 leuciscus Gthr., variat. elongata Steind."). 



Br achy deuf eras leuciscus Evermann and Radcliffe, 1917, p. 84, Tumbes and 

 Capon, Peru (synonymy; description; range). 



Pomadasys leuciscus Meek and Hildebrand, 1925, p. 551, Panama Bay (synon- 

 ymy, P. nitidus apparently wrongly included; description; range). 



Head 2.8 to 3.2; depth 3.0 to 3.1; D. XII, 14 or 15; A. Ill, 7 or 

 8; P. 17; scales 50 to 54. 



Body rather strongly compressed, its greatest thickness about half 

 its depth; back elevated; profile over head nearly straight; ventral 

 outline in advance of anal nearly straight; caudal peduncle long, 

 compressed, 2,7 to 3.4 in head; snout moderately pointed, increasing 

 in proportionate length with age, 2.5 to 3.5; eye 3.7 to 4,7; inter- 

 orbital 5.2 to 5.6; preorbital increasing greatly in width with age 



