226 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



lary spines extend upward till above eye, closing deep groove on top 

 of head. Maxillary without supplemental bone, not slipping below 

 very narrow preorbital, its surface silvery like rest of head and slit 

 between base of mandible and preorbital to permit its free motion. 

 Teeth in jaws slender, villiform, none on palate or tongue. Nostrils 

 rounded, double. Opercle without spine. Preopercle usually entire, 

 sometimes serrate. Gill membranes separate, free from isthmus. Gill 

 rakers short, broad. Pseudobranchiae concealed. Branchiostegals 6. 

 Lower pharyngeals close together, often appearing united, teeth 

 blunt. Air bladder present. Pyloric coeca small, few, about 3. 

 Vertebrae 23 or 24, of which 13 to 14 caudal. Oviparous. Scales 

 moderate, deciduous, cycloid or minutely ctenoid. Lateral line com- 

 plete, concurrent with profile of back. Dorsals and anals with basal 

 scaly sheaths into which fins depress partly or entirely. Dorsal fin 

 single, continuous or deeply notched, spinous and rayed portions 

 equally developed. Dorsal spines usually 9, sometimes 10. Anal 

 spines usually 3, sometimes 2 or 6. Ventrals thoracic, with spine and 

 5 rays, rather close together and slightly behind pectorals. 



Usually small or moderate sized fishes of the tropical and temperate 

 seas of the globe. They are very similar in general appearance, in 

 this respect recaUing such families as the Leiognathidae and Chand- 

 idae. Often the structural characters of the genera, though subtle, 

 are well defined. All are more or less bright to brilliant silvery white, 

 and some may be marked with shghtly darker longitudinal or trans- 

 verse lines, bands, or blotches. None display brilliant contrasted 

 colors. They abound frequently in great numbers about sandy shal- 

 lows, where they are said to spawn and feed. The food is small marine 

 invertebrates. Most are valued as food fishes, but as they soon spoil 

 in warm countries they must be eaten fresh. 



ANALYSIS OP GENERA 



o'. Gerrinae. Anal fin short, of 2 to 4 spines and 7 to 10 rays. 

 6'. Anal spines 3. 



d. Preopercle edge entire Qerres. 



c^. Preopercle edge serrate Diapterus. 



62. Anal spines 4; preopercle edge entire or serrate Qerreomorpha. 



o*. Pentaprioninae. Anal fin long, spines usually more than 3, rays 13 to 17. 

 d\ Spinous dorsal and anal higher than raj^ed fins; anal spines 5 or 6; 



pectoral long, falcate, much longer than head Pentaprion. 



<P. Vertical fins uniform in height; anal spines 3; pectoral shorter than 

 head Parequula. 



Genus GERRES Quoy and Gaimard 



Gerres (Cuvier) Quoy and Gaimard, Voy. Uranie, Zool., p. 292, 1824. (Type, 

 Gerres vaigiensis Quoy and Gaimard, monotypic.) (No generic description.) 



Gerris Swainson, Nat. Hist. Animals, vol. 2, p. 28, 1839. (Type, Gerres vaigiensis 

 Quoy and Gaimard.) (Error: Not Gerris Fabricius, 1794.) 



Podager (not Wagler, 1832) Gistel, Naturg. Thierreich, p. ix, 1848. (Type, 

 Gerres vaigiensis Quoy and Gaimard, virtually, as Podager Gistel proposed 



