JO Memoirs of the Indian Museum. |Vol. Ill, 



Family II, Baustidae. 



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 . . . . Batistes. 



B.— One perfect and usually one rudimentary dorsal 

 spine. 

 (/;) Ventral spine present or absent; no barbel; less 



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



{b') No ventral spine; no barbel; more than 40 rays 



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



(//') 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 single series . . . . Ostracion. 



The above key is based on the one given by Giinther 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 Triacanthus, Cuvier. 



Key to the Indian species of Triacanthus. 



A. — 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. 



B. — Second dorsal spine less than half as long as the 

 first. 



[h) Membrane of dorsal fin entirely pale; first dorsal 

 spine distinctly longer than the head ; snout 

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



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

 not longer than the head; snout stout, with 

 the dorsal profile nearly straight . . T. brevirostris. 



