298 



Key to the indo-australian species of 

 R h o m b a 1 1" a c t u s. 



I. Lower jaw somewhat prominent. L.l. 30 — 32. Origin 

 of anal opposite to that of first dorsal. Anal with 



17 — 21 rays. Pectorals shorter than head without snout. Rh. praecox p. 298. 

 II. Upper jaw prominent. L.l. 32 — 40. 



A. Second dorsal with 18 — 21 rays. L.l. 38 — 40. Origin 

 of anal in front of first dorsal. Pectorals equal to 

 head without snout. A vertical black band between 



black lateral band and base of anal Rh. vanheiirni p. 299. 



B. Second dorsal with less than 18 rays. L.l. with 

 less than 40 scales. Origin of anal in front of, 

 opposite to or somewhat behind tliat of first dorsal. 

 Pectorals longer than head without snout. No ver- 

 tical black band. 



1. L.l. 37 — 39. Origin of anal decidedly in front 

 of that of first dorsal. 17 — 19 praedorsal scales. 



a. Dorsal profile convex. Caudal peduncle as 

 high as long or higher than long. Second 



dorsal with 15 — 17 rays. A. I. 23 — 30 Rh. loreiitzi p. 300. 



b. Dorsal profile straight or even concave. Caudal 

 peduncle longer than high, in very large 

 specimens as high as long. Second dorsal with 



II — 14 rays. A. I. 21 — 25 Rh. hochi p. 302. 



2. L.l. 32 — 36. Origin of anal below or slightly 

 before or behind that of first dorsal. 15 — 16 prae- 

 dorsal scales. 



a. Caudal peduncle considerably higher than 

 long, longer than high in small specimens. 

 Snout shorter, more obtuse. Second dorsal 

 with II — 13 rays. No teeth on tongue. Spine 



of first dorsal much shorter than that of anal. Rli. catherinac p. 303. 



b. Caudal peduncle as long as high, higher than 

 long in very large, longer than high in small 

 specimens. Snout longer, more pointed. Second 

 dorsal with 12 — 16 rays. A patch of teeth 

 on base of tongue. Spine of first dorsal much 



longer than that of anal Rh. goldiei p. 304. 



I . Rhombatractus praecox n. sp. 



DM. 3— 5; D-. I. 10— 14; A. I. 17— 21; P. II — 13; V. 1.5; 

 L.l. 30 — 32; L.tr. II — 12. 



