Memoirs of the Indian Museum. 



[Vol. Ill, 



Family II, Baustidak. 



Skin rough or with moveable scales ; body compressed ; not more than three spines 

 in the dorsal; ventral reduced to a single spine or absent. 



A. — Three dorsal spines present . . . . Balistes. 



B. — One perfect and usually one rudimentary dorsal 

 spine. 

 {b) Ventral spine present or absent; no barbel; less 



than 40 rays in the anal fin . . . . Monacanthus. 



(&') No ventral spine; no barbel; more than 40 rays 



in the anal fin . . . . . . Aluteres. 



{b") No ventral spine; a fleshy barbel on the lower 



jaw . . . . . . , . Anacanthus. 



Family III, Ostraciontidae. 

 The scales modified into a firm and inflexible carapace formed of mosaic-like 



scutes; spinous dorsal and ventral fins absent. 

 Teeth small, slender, in a smgle series 



Ostracion. 



The above key is based on the one given by Günther in his Catalogue (vol. viii, 

 p. 208), but only Indian forms are included and certain modifications have been ren- 

 dered necessary by more recent work on Oriental ichthyology. 



Family TRIACANTHIDAE. 



Genus Tri acanthus, Cuvier. 



Key to the Indian species of Triacanthus. 



—Second dorsal spine much more than half as long 

 as the first. 

 First dorsal spine shorter than the head ; membrane 



of the dorsal fin tipped with black . . T. strigilifer. 



—Second dorsal spine less than half as long as the 

 first. 

 (Ô) Membrane of dorsal fin entirely pale; first dorsal 

 spine distinctly longer than the head; snout 

 fairly stout; dorsal profile of head sinuous . . T. oxycephalus. 

 (b') Membrane of dorsal fin black; first dorsal spine 

 not longer than the head; snout stout, with 

 the dorsal profile nearly straight . . T. brevirostris. 



