254 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. xxv. 



Family II. BALISTID^. 



TRIGGER FISHES. 



Bod}^ oblong, or ovate, moderately compressed, covered with rather 

 large rough scales or scutes of varj'ing form, the scutes not forming 

 an immovable carapace. Lateral line ol)scure or wanting. jNIouth 

 small, terminal, low; Jaws short, each with a))out 1 series of separate 

 incisor-like teeth; eye near occiput; preorbital ver}^ deep. Chin with- 

 out barbel. Gill openings small, slit-like, above or in front of pecto- 

 ral fins, and not before eyes. Dorsal fins 2, the anterior of 2 or 3 

 spines, the first spine highest, very strong, the second locking it in 

 erection; second dorsal remote from the first, of many soft rays; cau- 

 dal fin rounded or forked; ventral fins wantin^g, their place occupied 

 by a single stout, thick spine at the end of the very long, usually 

 movable pubic bone. Post-temporal short, simple, the forks obliter- 

 ated, the bone grown solidly to the skull, and with no foramen. Ver- 

 tebra? in reduced number (17). Shore fishes of the tropical seas, of 

 rather large size, carnivorous, or partly herbiverous, ver}' rarely 

 used as food, man}^ of them reputed to be poisonous, 

 a. Caudal peduncle compressed. 

 h. Teeth white or pale, not red. 

 r. Teeth unequal, oblique, each one deeply notched. 



d. Gill opening with a number of enlarged bony plates or scutes behind it; 

 ventral flap movable, supported by a series of spines, more or less free at 

 tip, and resembling fin rays. 

 e. Dorsal and anal fins low and rounded, their angles and those of caudal 

 not produced ; lateral line obsolete or with a trace at the shoulder; scales 

 of posterior parts each with a l)lunt spine or tubercU;; ventral flap narrow, 

 its supporting spines stout and thick in the adult; third dorsal spine 

 small. 

 /. Eye with a naked groove before it. 



(J. Cheeks with small scales closely set; snout scaly Pachynathuif, 3. 



gg. Cheeks with large scales loosely set; snout nak^ed. .PseiidohidiMit^, 4. 



ff. Eye without preocular groove BalisUtpm, 5. 



dd. Gill opening Avith only ordinary scales behind it; no enlarged plates or 

 scutes; ventral flap scarcely movable, its surface scaled; lateral line 

 obsolete; third dorsal spine small or wanting; vertical fins in adult more 

 or less angulate or falcate. 



h. Chin not projecting; cheeks closely scaled; dorsal spine 3; scales 

 of posterior parts unarmed or keeled Canthidermis, 6. 



3. PACHYNATHUS Swainson. 



Pachynathw^ Swainson, Classn. Fishes, II, 1839, p. 326 {triangidaris=capistratus; 

 the name evidently an error for Pachygnathus, but not so spelled; not 

 Pachygnathus, an earlier name of a genus of spiders.) 



This genus difi'ers from Balistes in the rounded outlines of the ver- 

 tical fins and in the possession of small spines or tubercles on the 

 scales of the caudal region. Ventral fiap somewhat movable, its sup- 



