THE MOjARRAS 



Family LIV. Gerridce 



BODY oblong or elevated, covered with large, smooth scales; 

 lateral line continuous, concurrent with the back; mouth moderate, 

 extremely protractile, descending when protruded, the spines of the 

 premaxillary extending to above eye, closing a deep groove in top 

 of head; maxillary without supplemental maxillary bone, its surface 

 silvery like the rest of the head; base of mandible scaly; jaws with 

 slender, villiform teeth; no incisors, canines, nor molars; no teeth on 

 vomer or palatines; preopercle entire or serrate; sides of head scaly ; 

 dorsal fin single, continuous or deeply notched, the spinous and soft 

 parts about equally developed, a scaly sheath along the base; dorsal 

 spines usually 9 or 10; anal usually with 3 spines, the soft anal similar 

 to the soft dorsal but shorter. 



This family contains 6 to 8 genera and about 40 species, all car- 

 nivorous fishes of moderate or small size, inhabiting tropical seas. 



In our waters 4 of the genera are represented by 17 species, the 

 larger ones being used as food. None of them, however, is of great 

 importance, and they have no value as game-fishes. 



a. Second interhaemal spine singularly developed as a hollow cylinder, 



comparatively short and much expanded, the posterior end of 

 the air-bladder entering its cavity; preopercle and preorbital 

 entire; anal spines 3, the second not much enlarged. 



Eucinostomus, 445 



aa. Second interhaemal spine normally developed, not hollow, the air- 

 bladder not entering it. 



b. Second interhaemal spine very short, bluntish; anal spines 2, both 



small ; preopercle and preorbital entire Ulcema, 447 



bb. Second interhaemal spine long, spear-shaped; anal spines 2 or 3, 

 the second enlarged. 



c. Preopercle entire; second anal spine moderate Xystcema, 447 



cc. Preopercle serrate; second anal spine much enlarged. .Gerres, 447 



GENUS EUCINOSTOMUS BAIRD & GIRARD 



The Mojarritas 



This genus, sufficiently defined in the preceding key, is repre- 

 sented in our waters by 5 species, which may be distinguished as follows : 



445 



