NATURAL SCIENCES OF PHILADELPHIA. 145 



Orbit Diameter 4 J 



Distance from snout 9 



" " profile 3 



" above preoperculum 8 



Dor3al Distance from snout 21 



Length of spinous part 25 



soft part 29 



Anal Distance from snout 42 



Length 33 



Caudal Length 17 



Pectoral Length 16 



Ventral Length 9 



Numerous specimens were obtained by Mr. Xantus, but most of them are 

 very small ; the largest is less than four inches long. 



Genus INIISTIUS Gill. 

 Iniistius mdndicoupds Gill. 

 This species has the same form of the head and body as Iniistius pavo. The 

 greatest height equals three-tenths (-30) of the length and that of the caudal 

 peduncle a ninth (.11) ofthe same. The head forms less than three-tenths ( - 28) 

 of the length, and is equal to the height over the preoperculum. The eye is 

 small, its diameter entering seven times (-4) in the bead's length; it is distant a 

 diameter from the profile. The height of the preorbital equals a tenth (-10) of 

 the total length. The front teeth ofthe upper and lower jaws are nearly equal, 

 and those of the latter are received between those of the former. The anterior 

 occipital spine equals the length of the pectoral and nearly a fifth (-19) of the 

 total. The ventrals exceed a seventh (-15) of the length and are inserted en- 

 tirely under the upper angle of the base of the pectoral. The caudal scarcely 

 forms a seventh ( - 14) ofthe length. 

 1 1 



D. II. VII. 22, 19 -. A. 3, 11 -. C. 2, 5, 5, 2. P. 2, 10. V. I. 5. Scales 

 1 1 



2 3 2 



24 . 25 inclusive of large one on caudal, behind occipital fin ; at anus-. 

 10 10 8 



The body is yellowish or brownish and entirely immaculate. The dorsal 

 alone has several oblique bars between its rays. 



One specimen, nearly ten inches long, was obtained by Mr. Xantus at Cape 

 St. Lucas, and is now in the Museum of the Smithsonian Institution. The 

 right front tooth ofthe lower jaw is deflected forwards horizontally. 



Family POMAGENTROIDM. 



Genus EUSCHISTODUS GUI* 



This name is appropriated to a group of Pomacentroids having nearly the 

 same physiognomy as Hypsypops, but the teeth, instead of being entire, are very 



* A second species of this genus is an inhabitant of Panama, where it was discovered 

 by Capt. J. M. Dow. 



The forehead is transversely convex but not arched, the profile in front less steep, the 

 preorbital higher behind, and the caudal peduncle shorter than in Euschiatodusdeclivifrons. 



D. XIII. 12. A. II. 10. 

 4 3 



Scales 26 , L. 1. 21. 



10 3 



The color is uniformly chocolate or purplish brown ; the bases of the pectorals with 

 falciform black line pointed below. 



The species may be named Euschislodus concolor. 



1862.] 10 



