218 PROCEEDINGS OF THE ACADEMY OP 



and Panama, varying from ten lines to two inches and a half in length, and 

 have been thus enabled to study the development of the coloration, which is 

 quite peculiar in the gradual spreading of the blue, while it becomes fainter 

 at the same time with age. The species is closely allied to the P. quadrigutta, 

 having nearly the same height, the naked lower limb of the preoperculum, 

 and the pattern of the upper surface of the head. It has high preorbital bones , 

 and a wide convex forehead. 



The specimen mentioned under this name in Dr. Giinther's Catalogue, can 

 scarcely belong to it, as that author would otherwise not have confounded it 

 with the P. rectifr&num, which belongs to a different genus. The name under 

 which the P. Bairdii was sent has doubtless by some accident been shifted to 

 the young of P. reclifrienum, and the specimen of the former lost. 



Genus HYPSYPOPS Gill. 

 Synonymy. 

 Hypsypops Gill, Proc. Academy of Natural Sciences of Phila., 1861, p. 165. 

 Hypsypops Gill, op. cit., 1862, p. 147. 

 Glyphisodon sp. Girard. 

 Parma sp. Giinlher. 



Body oblong-oval, with the dorsal and inferior outlines correspondent, 

 rapidly contracted under the soft dorsal and anal fins, constricted behind 

 those fins, and with the caudal peduncle short and high. 



Scales little or no higher than long, subpentagonal, with a muricated bor- 

 der behind ; arranged in less than thirty oblique rows, and about twenty 

 longitudinal ones. Smaller ones extend far on the vertical fins. Lateral line 

 tubular, terminated under the posterior portion of the dorsal fin. 



Head rather higher than long, constricted at the nape, with the forehead 

 prominent, in front of which the profile is steep, but depressed, and the 

 snout protuberant and jaws rounded. Infraorbital chain in front elevated, 

 higher than the diameter of the eye, subangulated at the corner of the mouth, 

 and thence trending very obliquely upwards and backwards, under and be- 

 hind the eye. Eyes rather small. Preoperculum unarmed ; operculum with 

 a bony projection behind. Cheeks with rather small scales ; operculum and 

 suboperculum with large ones. Preorbital, and region in front of forehead, 

 naked. 



Mouth small, with its periphery semioval, and the supramaxillaries ceasing 

 in front of the eyes ; little retractile under preorbital ; surmounted by a strong 

 ridge. Lips rather thick, continuous at angle with each other j lower free all 

 around. 



Teeth fixed, uniserial, contiguous, narrow, blunt and entire ; in a short, 

 semioval row, and behind deflected outwards and downwards on the upper 

 jaw ; In the lower, in an oblong, semioval row. 



Branchiostegal rays five. 



Dorsal fin with twelve subequal spines, and the soft portion produced in 

 front of the middle and emarginated behind. 



Anal fin armed with two stout spines, and with a soft portion like the dorsal. 



Caudal fin notched, with the lobes rounded. 



D. XII. 16. A. II. 15. C P. V. 1. 5. 

 5 



Scales 28 

 14 



Hypsypops rubicdndus Gill. 



Synonymy. 

 Glyphisodon rubicundus Girard, Proc. Academy of Natural Sciences of Phila., 

 Vol. vii. p. 148, 1854. Girard, Explorations and Surveys for a Railroad 

 Route, &c, vol. x. Fishes, p. 161, pi. xxiv. Girard, op. cit., vol. x. 

 Whipple's Report, Zoology, p. 51. 



[Sept. 



