Ulsema 



GENUS UL/EMA JORDAN & El/ERMANN 



This genus is dose to Eucinostomus, from which it differs in the 

 form of the second interhsemal. The single species (Ulcema lefroyi) 

 is known from the Bermudas, the West Indies, and north on sandy 

 shores to Cedar Keys. It reaches 8 inches in length, and is plain sil- 

 very in colour. 



GENUS XYST/EMA JORDAN r EYERMANN 



This genus differs from Gerres in having the preopercle entire. 

 The single species (Xystcema cinereum) is found on both coasts of trop- 

 ical America, north to Lower California and southern Florida. It is 

 generally common in water of moderate depth, and ascends rivers con- 

 siderable distances. It reaches a foot or more in length, and is a food- 

 fish of no little importance. In Porto Rico, where it is common, it is 

 called muniama. 



GENUS GERRES CUYIER 



This genus, distinguished by the long spear-shaped interhsemal, 

 contains 10 American species. 



a. Preorbital entire; no distinct dark streaks along rows of scales. 



b. Anal spines 2, the rays 9 rhombeus, 448 



bb. Anal spines 3, the rays 8. 



c. Premaxillary groove broad, triangular or oval, and free from scales. 



d. Body ovate, the outline somewhat regularly elliptical, the depth 2\ 



in length aureolus, 448 



dd. Body rhomboidal, short and deep, with angular outlines, the 



depth usually more than half the length peruvianus, 448 



cc. Premaxillary groove broad, oval, and covered with scales. 



olisthostomus, 448 

 aa. Preorbital serrate; a distinct dark streak along each row of scales. 



e. Scales moderate or large, 34 to 39 in lateral line. 



/. Spines moderate, the second dorsal f to f length of head. 



g. Pectoral short, barely reaching vent; second dorsal spine if in head; 



caudal shorter than head brevimanus, 449 



gg. Pectoral at least as long as head; caudal longer than head. 



k. Pectoral as long as head, not reaching anal, 3 to 3$ in body; scales 



38. 



447 



