342 PKISTIPOMATID^. 



the head ; the second of the anal three-fourths of the second of the 

 dorsal. Silveiy ; dorsal with a blackish margin. 

 Atlantic coasts of Tropical America. 



a. Fine specimen. Cuba. Presented by the Zoological Society. 

 h-f. Adult and haK-grown : skins. Jamaica. Fi'om Dr. Parnell's 



Collection. 

 (J. Adult : not good state. Puerto CapcUo. Purchased of Mr. Brandt. 

 /; . Adult : not good state. South America. Purchased of Mr. Brandt. 

 /-?. Adult: not good state. South America. Purchased of Mr. Brandt. 

 m. Half-groMTi. South America. Presented by Sii- R. Schomburgk, 

 n. Adult : skeleton. From the Haslar Collection. 

 0. Adidt : skeleton. From the Collection of the Zoological Society. 

 p. Half-grown. From the Haslar Collection. 

 q. Young. 



Sl'cJeton. — I have had skeletons of the fish prepared with two 

 anal spines as well as with thi-ee, and having found them exactly 

 alike, I am fully convinced that the form with two anal spines is 

 merely accidental in some individuals, and that G. rJiombeus of Cuvier 

 must be considered as a nominal species. I have, however, preferred 

 the name of G. rhomheus to that of G. hrasiUensis. 



The skeleton differs from that of G. plumieri in several points. 

 The maxillary bone is vei-j- irregularly shaped, and exhibits a thick 

 protuberance in the middle of its outer surface ; this is, however, 

 more conspicuous in very old specimens. The intermaxillaries and 

 the manchbula are very much like those of G. plumieri. The prse- 

 orbital has the maxillary margin concave and entire ; its posterior 

 |)art is rather broader than the remainder of the infraorbital arch. 

 The head of the vomer is rather flat, without a distinct prominence ; 

 the palatiae bones exhibit a shght groove. Both the margins of the 

 pi'fEoperculum are straight ; the angle is rounded, and like the inferior 

 limb armed with a very distinct and equal serrature ; the posterior 

 limb is entire. The remainder of the opercular apparatus as in 

 G. plumicii. The occipital crest extends fui-ther forwards than in 

 G. plumieri, the anterior groove being situated above the anterior 

 portion of the frontal bones ; there is, besides, this peculiarity in 

 G. rJiornbeus, that the groove mentioned commimicates with the 

 orbital cavity by a pair of large oval holes. 



There are nine abdominal and fifteen caudal vertebne ; the length 

 of the former portion of the vertebral cohunn being to that of the 

 caudal as 1 : 1-8. The ribs are rather feeble, Avith a posterior and 

 anterior longitudinal groove ; the fii'st three ribs are very slender, 

 short, and without a prominent knob. The neural spines become 

 gradually longer to the thii'teenth vertebra, and are furnished with a 

 more or less chstinct, flat, transparent, posterior ridge. The inter- 

 neiu'al spines do not differ from those of G. pjlumieri, except that of 

 the second dorsal spine, which, like that spine itself, is not quite so 

 strong. The first interhiemal is exceedingly strong, and has in front 

 a very broad and emarginate ridge ; its length equals that of the 

 first nine vertebrae. 



