Jordan and Evermann, Fishes of North America. 1375 



head; anal spines constantly 2 in number, the second If in length of 

 head. Color silvery, with bluish reflections, darker above ; margin of dor- 

 sal fin black; fins rather pale; ventrals and anal with dusky punctula- 

 tions; snout dusky; no distinct dark lines along the rows of scales. 

 Length 8 to 10 inches. West Indies and Atlantic coast of tropical Amer- 

 ica; generally common; known from Jamaica, San Domingo, Martinique, 

 Puerto Cabello, Havana, Aspinwall, Rio Magdalena, Santa Lucia and 

 Bahia. Easily known by the presence of but 2 anal spines, (rhombeus, 

 rhombic.) 



Gerres rhombeus, CUVIER & VALENCIENNES, Hist. Nat. Poiss., vi, 459, 1830, Martinique; 

 San Domingo; GUNTHER, Cat. Fishes, i, 341, and iv, 253 ; EVERMANN & MEEK, I. c., 266. 



Subgenus DIAPTERUS,* Ranzani. 

 1751. GERRES AUREOLUS, Jordan & Gilbert. 



Head 3 ; depth 2 ; eye 3 in head. D. IX, 10 ; A. Ill, 8 ; scales 35. Body 

 ovate, much compressed, the back elevated, the outlines nearly regular; 

 outline along base of anal very oblique; caudal peduncle very short and 

 deep, tapering regularly to base of tail; snout rather pointed, projecting, 

 the interorbital area strongly depressed; maxillary long, reachiug to a 

 point midway between front and middle of pupil, the exposed portion 

 narrowly oblong, its width about its length ; teeth slender, in narrow 

 bands; groove on top of head for premaxillai ies scaleless, triangular, 

 reaching a point opposite middle of eye, its width in front its length. 

 Eye very large, its diameter greater than snout or than interorbital 

 width. Preopercle with angle produced, the margin sharply and finely 

 serrated. Gill rakers very short, not diameter of pupil. Scales moder- 

 ate, in about 4 rows on the cheek; lateral line running high, but little 

 arched much above axis of body, even on caudal peduncle. Dorsal spines 

 slender, but little flexible, the second scarcely stronger than the others, 

 about as long as the third, | as long as head; dorsal fins separate, 

 notched to the base, the upper outline of spinous portion very oblique; 

 caudal deeply forked; anal low, the second spine a little longer and 

 noticeably stronger than the third, 2f- in head; soft rays posteriorly not 

 rising above their basal sheath of scales ; ventrals reaching well past vent, 

 their length more than | head; pectorals long, as long as head, reaching 

 slightly beyond origin of anal. Color iu life, light olivaceous above, 

 silvery below ; sides with distinct tinge of pale yellow; fins all yellowish; 

 vertical fins margined with black, the spinous dorsal with a jet-black 

 blotch on tip of membrane of anterior spines ; membrane of each spine 

 and ray of the dorsal with a distinct jet-black spot at its base; ventrals 

 yellow on terminal portion of outer rays only, the very tip of these white; 

 tip of snout dark; opercular membrane yellowish above; lips with some 



* Diapterus is thus defined by Ranzani : 



* ' Caput breve frons basi concava, rostrum attenuatum. Dentes maxilla-res minutissimi, 

 atque confertissimi ; Membrana branchiostegia septem radiis fulcita. Corpus valde com- 

 pressum et elevatum. Secunda pinna dorsalis, nee aualis in pinnulas divisa. 



Hujus generis una tantum species adhuc mibi innotuit, quam appelavi Diapterum, aura- 

 turn, ejusque imaginem verbis mine exprimere conabor." 



