BULLETIN OF THE UNITED STATES FISH COMMISSION. 329 



portion very oblique. Caudal deeply forked. Aual 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. Ven- 

 trals reaching well past vent, their length more than half head. Pec- 

 torals long, as long as head, reaching slightly beyond origin of anal. 



Head 3 in length ; depth 2^. D. IX, 10 ; A. Ill, 8 ; Lat. 1. 35. 



Color in life : Light olivaceous above, silvery below, sides with distinct 

 tinge of pale yellow. Fins all yellowish; vertical fins margined An th 

 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. Yentrals 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 yellow. 



A single specimen, 5^ inches in length, was taken in the Bay of 

 Panama. 



The species of Gerres found on the Pacific Coast of tropical America 

 may be thus compared : 



a. Preopercle entire ; anal rays III, 7 ; body rather elongate ; dorsal and anal spines 

 comparatively low. 

 &. Furrow on top of bead for premaxillary processes long and narrow, naked ; tip 

 of spinous dorsal more or less abruptly black (this black spot ocellated 

 in the males) ; teeth not very small, 

 c. Body elliptical, strongly compressed, the profile not steep; depth little more 

 than one-third of length ; cheeks and sides without dark puuctulations ; 

 lower tins pale; head small, 3| in length ; eye barely one-third length of 



head * Gracilis.* 



cc. Body subelliptical, deejjer, and less comi)ressed, the profile rather steep ; depth 

 nearly two- fifths of length ; cheeks and sides "with dark puuctulations; 

 head rather large, 3^^ in length ; eye more than one-third length of head. 



Dowi.t 

 hi). Furrow on top of head for premaxillary processes, short and broad, posteriorly 

 semicircular or subtriangular, naked ; tip of spinous dors.il becoming grad- 

 ually dusky; teeth small. 

 d. Body moderately elevated, the depth barely two-fifths of length ; caudal fin 

 moderate, shorter than head ; second anal spine not very strong, shorter 

 than third, about one-fourth length of head ; ventrals short, little more 

 than half length of head, not reaching vent ; sides without dark bars. 



Californiensis. X 



dd. Body more elevated, the depth about two-fifths the length ; caudal fin long, 



usually longer than head ; second anal spine very strong, longer than 



third, one-third or more length of head ; ventrals long, two-thirds head, 



reaching vent; sides with 8 or 9 dark vertical bars Zebra. $ 



* Diapterus gracilis Gill, Proc. Ac. Nat. Sci. Phila. 1862, 240. Cape Sau Lucas (Gill)] 

 Guaymas (Kichols coll.); Mazatlan {Gilh.)\ Panama (Gilb.). 



\ Diapterus doivi Gill, Proc. Ac. Nat. Sci. Phila. 1863, 162. Panama {Gill, Steind. 

 Gilb.) ; Galapagos Islands (Steind.). 



t Diapterus californiensis Gill, Proc. Ac. Nat. Sci. Phila. 1862, 245. Cape San Lucas 

 {Gill); Guaymas {Nichols coll.) ; Mazatlan {Gilb.). 



^Gerres zebra Miiller &. Troschel, Schomburgk Hist. Barbadoes, 1848, 668: Gerres 

 squamipinnis Giiuther, i, 349, 1849. West Indies; Mazatlan {Gilb.): Chiai>am {Gihr.); 

 Panama {Gihr.). 



