202 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



D. XI, 11, I, fourth spine 1% to 1% in head, first ray 2% to 2%; 

 A. Ill, 10, I, second spine 2 to 2%, first ray 2 to 2}^; caudal 1, deeply 

 emarginate, broad lobes pointed; least depth of caudal peduncle 2}^ 

 to 2%; ventral 1}^ to 1%; pectoral 2% to 3 in combined head and body. 



Back brown to dull olivaceous, sides below and under surfaces 

 white. On back and sides each row of scales with sUghtly darker 

 narrow median longitudinal line or narrow band. Iris whitish. Fins 

 all pale, dorsals darker or slightly dusky terminally, especially on 

 spinous fin; each membrane with more or less distinct brownish sub- 

 basal small spot. Caudal slightly darker behind. 



Red Sea, Arabia, Mozambique, Natal, Aladagascar, Melo-an, India, 

 Nicobars. 



U.S.N. M. No. 49290. Red Sea. Bellotti. Length, 124 to 138 mm. Two 



examples. 

 A.N.S.P. No. 53099. Delagoa Bay. H. W. Bell Marley. Length, 154 mm. 

 A.N.S.P. No. 53014. Durban, Natal. H. W. Bell Marley. 1927. Length, 226 mm. 



Genus TRIPTERODON Playfair 



Tripterodon Playfair, Fishes of Zanzibar, p. 42, 1866 (Type, Tripterodon orbis 

 Playfair, monotypic.) 



Body orbicular, greatly compressed. Head small, deep. Snout 

 short. Mouth cleft narrow, short. Large movable tricuspid teeth 

 in several rows in both jaws. Palate toothless. Cheek deep, depth 

 over twice orbit. Gill opening moderate, separated by broad isthmus. 

 Gill membranes not extending across throat. Scales moderate. 

 Soft vertical fins finely scaled. Dorsal spines with 3 to 5 produced, 

 others short. Caudal emarginate. Pectoral small, much shorter 

 than head. Ventral large, with first ray as short filament. 



TRIPTERODON ORBIS Playfair 



Tripterodon orbis Playfair, Fishes of Zanzibar, p. 42, pi. 7, fig. 1, 1866 (type local- 

 ity: Zanzibar). — Fowler, Proc. Acad. Nat. Sci. Philadelphia, 1925, p- 

 242 (Delagoa Bay). — Barnard, Ann. South Afric. Mus., vol. 21, pt. 2, 

 p. 725, 1927 (Delagoa Bay). 



Depth IK; head 3K, width 2. Snout 1% in head; eye 3%, 2 in snout, 

 1% in interorbital ; maxillary reaches opposite hind nostril, expansion 

 y2 eye, length ^% in head; teeth tridentate incisors, 4 rows in each jaw; 

 interorbital 2% in head, convex, slightly gibbous. Gill rakers 1 + 10, 

 short points. 



Scales 45 in lateral line; 7 above, 21 below; soft vertical fins densely 

 scaled. Scales with 4 basal radiating striae; 57 to 65 apical denticles, 

 with 3 to 18 transverse series of basal elements; circuli fine. 



D. IX, 20, 1, third spine 2% in combined head and body to caudal base, 

 fourth ray 1% in head; A. Ill, 16, i, second spine 3K, third ray 1}^; 

 caudal 1, emarginate; least depth of caudal peduncle 2%; pectoral 

 1%; ventral 2% in combined head and body to caudal base. 



