Fam. XVIII. Centropomid^e. Fam. XIX. H^emulid^e. 199 



a strong supplemental bone; preopercle with a double ridge, the 

 posterior margin strongly serrate ; opercle without true spines ; scales 

 ctenoid; lateral line conspicuous; dorsal fins well separated, the first 

 with 8 spines; anal spines 3, the second strong, the third long and 

 slender; these fins moving in scaly sheathes; air bladder well devel- 

 oped; branchiostegals 7. Species all American, one species found in 

 the rivers of southeastern Mexico far above tide-water. 



78. Centropomus Lacepede. 

 Robalos. 



Centropomus Lacepede, Hist. Nat. Poiss., iv, 248, 1802. (Type re- 

 stricted by Cuvier & Valenciennes to Scicena undecemalis Bloch) . 

 Characters of the genus are included in the description of the family. 



188. Centropomus mexicanus Bocourt. Robalo. 



Centropomus mexicanus Bocourt, Ann. Sci. Nat. Paris, 1868, 90; 

 Gulf of Mexico: Vaillant & Bocourt, Miss. Sci. Mex., 1875, 23, 

 pi. 1, fig. 2: Jordan & Evermann, Bull. 47, U. S. Nat. Mus., 

 1896, 1 121. 



Both coasts of Mexico, ascending rivers to a considerable distance 

 above tide-water. (San Francisco; Boca del Rio; El Hule; Perez.) 



Head 2^; depth 4 to 4^; D. viii-i, 10; A. in, 6; scales 11-69 

 to 7 2-16. Body elongate, moderately compressed ; mouth large, maxil- 

 lary reaching nearly to posterior margin of pupil ; preopercle with 

 sharp teeth on its posterior limb, the two at the angle larger than 

 the others; 2 spines at angle of anterior limb; diameter of eye 5X i n 

 head; third dorsal spine the longest, 2 in head; second anal spine 

 very strong, if in head; lateral line well developed; caudal fin forked. 



Color olivaceous, lighter below; lateral line blackish; tips of dorsal 

 and caudal blackish. Length 12 inches or more. 



Family XIX. HremulicUe. 



The Grunters. 



Body oblong, more or less elevated, covered with moderate sized 

 scales, usually ctenoid; lateral line concurrent with the back, usually 

 not extending on caudal fin ; head large ; no suborbital stay ; premaxil- 

 laries protractile; maxillary without supplemental bone, for the most 

 of its length slipping under edge of preorbital; preorbital usually 

 broad ; no barbels ; no teeth on vomer or palatines ; ventral fin thoracic, 

 its rays 1.5; pyloric ccecse few; vertebrae usually 10+14 = 24; alimen- 

 tary canal short. Mostly shore fishes, a few entering fresh water. 



