GIG CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IV. 



aa. Dorsal spines 8 to 11. (Poinacauthu?). 

 ?>6->. P. sireuatus (L.) Lac. 



Dark brown, anteriorly plain; lower jaw pale ; each scale witli adaik 

 spot and a whitish edge; young with yellowish vertical bands, some- 

 times spbtted with black; base of pectorals sometimes yellow. Scales 

 on body small, hrm; large and small ones irregularly mixed. Head with 

 shagreen, formed of rudimentary scales. Dorsal and anal extremely 

 falcate, the anterior soft rays two-thirds the length of the body in the 

 adult; dorsal spines very low; last anal spine long. Mouth small; 

 gill-rakers short; gill-membranes very slightly joined to the isthmus 

 mesially. D. IX, 30; A. Ill, 24; Lat. 1. 80-100; cceca 15; vert. 10 -f 

 14. Wt'st Indies, north to Garden Key, Florida. 



(Chcetodon arcuatus L. Syst. Nat.: Pomacaiithus paru, cingulatus, qiiinquecinctus, and 

 arcuatus Ciiv. & Val. vii, 202-211: Pomneantlms parti Giiiither, iii, 55.) 



Family XCIX.-x\CANTHURID^.* 



{The Surgeons.) 



Body oblong, compressed and usually elevated, covered with very 

 small scales ; lateral line continuous. Tail armed with one or more 

 movable spines or bony jdates. Eye lateral, high up; preorbital very 

 narrow and deep. Nostrils double. Mouth small, low; each jaw Avith 

 a single series of incisor-like teeth; vomer and palatines toothless; i)re- 

 maxillaries somewhat movable, but not protractile; maxillary short; 

 gill-rakers obsolete; pseudobranchi;e large; gills 4, a slit behind the 

 fourth; gill-membranes attached to the isthmus, the openings thus re- 

 stricted to the sides. A single d rsal flu, with strong spines, the spi- 

 nous part of the fin about as long as the soft part; anal fin similar, 

 shorter; ventral fins present, thoracic, mostly I, 5 (never I, 4, I, as in 

 Teuthidldcv). Pelvic bone long, evident thi ough the skin, as in BaUstidcc, 

 with which group the Acanthuridw have numerous affinities. Pyloric 

 (!oeca rather few. Air-bladder large. Herbivorous fishes of the tropicai 

 seas; genera 5 or more; species nearly 80, most of them belonging to 

 Acanthurus. 



(Acronuridas Giiutlier, iii, 356.) 



a. Tail Avitli a movable lancet-like spine on each side; incisors serrate. 



Acanthurus, 330, 



* Called Teuthidida' in the hey on page 78. 



