854 CONTEIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



lb. Supraocular spines present, strong, directed forward. {Acanihostrac'mm Bleeker.) 

 ISIY. O. quadricoriie l^.~Coiv-fish ; Cuclcold. 



Color browu, yellow, blue, or green, with irregular blue blotches; the 

 centers of the scutes often lighter than the margins. Carapace trigonal ; 

 adults with a broad low ridge on each side of the back, the dorsal ridge 

 more elevated than in the young, which are somewhat tetragonal. Ven- 

 tral surface nearly flat; angles of body carinate; a stout spine directed 

 forwards over each eye; abdominal spines flat, directed backward; me- 

 dian dorsal spine seldom present, never persistent; bridges behind dor- 

 sal and anal each ending in a flat spine; under side of caudal peduncle 

 with a free plate; carapace closed behind dorsal fin. Head 4|; depth 

 2^. D. 10; A. 10. Tropical parts of the Atlantic; common on our coast 

 southward. 



(Linnteus, Syst. Nat. x, 331, 1758; Giiuther viii, 257; Goode, Proc. U. S. Nat. Mus. 

 l!^79, 278.) 



Family CXXVIII.— BALISTID.E. 



{The Trigger -fishes.) 



Body oblong, or ovate, more or less compressed, covered with rough 

 scales or scutes of varying structure, the scutes not forming a carapace. 

 Mouth small, terminal, low; jaws short, each with one or more series of 

 separate incisor-like teeth ; eye near the occiput ; preorbital very deep. 

 Gill-openings small, slit-like, above or in front of the pectoral fins. 

 Dorsal fins two, the anterior of one to three spines, the first spine high- 

 est; second dorsal remote from the first, of many soft rays; caudal fiu 

 rounded or forked; ventral fins wanting, their place sometimes occu- 

 pied by a single spine at the end of the very long, usually movable, 

 pubic bone. Genera about 8; species about 100. Carnivorous fishes; 

 inhabitants of the warm seas. 



(Balislidw, group Balistina, Giiuther, viii, 211-255.) 



«. Dorsal spines three ; body covered with thick scales or plates. (Balistina.) 



Balistes, 477. 

 aa. Dorsal spine single or followed by a rudiment; skin with minute, rough scales. 

 (Moiiacanthuta;.) 

 I). Ventral spine present; gill-slit short, nearly vertical; anal rays about 30. 



MONACANTIIUS, 478. 



ib. Ventral spine obsolete; gill-slit long, oblique; anal rays about 40 to 50. 



Alutera, 479. 



477.— BAI.ISTES Liun^us. 



Triggerfishes. 



(Artedi; Linnteus, Sysftema Naturte, 1758: ty\\e Balistes vetulus "L.) 



Body compressed, covered with thick, rough scales or plates. Both 



