NATURAL SCIENCES OF PHILADELPHIA. 167 



times. The upper maxillary reaches nearly to the vertical from the hinder 

 margin of the orbit ; the intermaxillary enters 2J times in the head's length. 

 The snout is a little longer than the diameter of the eye ; the latter equals a 

 quarter of the head's length. The infraorbital bones do not extend to the 

 preoperculum ; the one above the maxillary bones is wider than the one above 

 itself and as wide as that behind the eye. The opercular apparatus is vertical 

 in front of the pectoral and for an equal space above. The preoperculum is 

 nearly vertical and its angle obliquely rounded. The width of the operculum 

 and suboperculum in front of the lower axilla of the pectoral equals the diam- 

 eter of the eye and the interval between suboperculum and axil. The pectoral 

 equals the interval between its axis and the hinder border of the pupil; the 

 ventral is rather shorter but its end almost or quite reaches to the anus. 



D. V. I. 20. (=9 -J- 11.) A. II. I. 20. (= 12+ 8.) G. 5. 1. 8. 7. 1. 4 P. 2. 

 14. V. I. 5. 



The color is uniform, tinged with blue above. 



One adult specimen is in the collection. It is very closely related to the 

 0. occidentalism f Chorinemus occidentalis C. & V.) of the Caribbean Sea but the 

 intermaxillar is shorter, the suboperculum wider and more convex below, the 

 opercular apparatus more truncated behind, and the anus and anal fin placed 

 farther forwards. 



The Western fishes referred to the genus Chorinemus by Cuvier and Valen- 

 ciennes do not appear to be congeneric with the Eastern and African species, 

 but rather constitute a peculiar genus distinguished by the fewer (4 5) dorsal 

 spine3. The names of Scomberoides Lac, Orcynus Raf., Chorinemus Cuv. and 

 Porthmeus C. et V., (young) have been applied primarily or wholly to the extra- 

 American species and cannot be retained for the American type. The Chori- 

 nemus occidentalis, C, guaribira C. et V., C. saliens C. et V. and C. palometa Cuv- 

 et Val., are the known species. 



Family EXOCCETOIDJE Bon. 



Genus EXOCCETUS Art. 



ExocffiTUS Down Gill. 



The greatest height is contained 5| times in the length to the fork of the 

 caudal, while the head forms little more than a fifth of the same length. The 

 width of the forehead equals of the head's length ; the diameter of the eye a 

 third. The scale in the middle of the forehead is transversely oblong and the 

 distance between its sides and the orbits about half as great as its width. The 

 four granulated areas in front are of small size ; the one behind larger and with 

 a smaller one on each adjoining lateral scale. The preoperculum is rectangu- 

 lar. The pectoral fin extends to the base of the caudal; the ventral fin is in- 

 serted nearly midways between the operculum and base of caudal and extends 

 about as far as the last anal ray bent backwards. 



D. 12. A. 12. C. 4. 1. 6. 8. 1. 6. 

 9 



Scales 50 

 2 



The dorsal commences over the twenty-eighth scale from the scapular region 

 and ends over the thirty-ninth. 



The pectoral fins are fuliginous, with light inferior border continued on 

 the lower rays. The ventrals are fuliginous, except on the base, inner ray 

 and distal margin. The caudal also fuliginous. The dorsal and anal are 

 colorless. 



One specimen nearly thirteen inches long is in the collection. 



Dedicated to the naturalist-collector, Captain Dow. 



ExOCffiTUS ALBIDACTYLUS Gill. 



The greatest height is contained nearly 6 times in the length to the fork of 

 1863.] 



