164 INDIAN FRESH -WATEB FISHES. 



I will next take into consideration the large and 

 important 



ORDER ACANTHOPTERYGII, 



or spiny rayed fishes. 



In most systematic works this order is placed first, 

 it does not, however, occupy such an important place 

 among the Indian fresh-water fishes as it does in 

 other parts of the world, and for this reason I have 

 placed them after the Physostomi. 



They are to be distinguished by having a number 

 of the rays of the dorsal and anal fins and often the 

 first ray of the ventral composed of strong sharp 

 spines. They have frequently two dorsal fins, but 

 both of them are composed of rays, and the adipose, 

 or gristly, fin does not appear in this order. When 

 v here are two dorsal fins, the first is composed 

 entirely of spinous rays ; or the two fins may be 

 united. The Ophiocephalidie appear at first sight to 

 be exceptions to the general rule, inasmuch as they 

 have no spinous rays in any of their fins. There is 

 no doubt, however, of their belonging to this order, 

 and we may conclude, as occurs in some other cases, 

 that the first dorsal fin is wanting, or perhaps on 

 account of their burrowing habits, the soft portions of 

 their fins may have become developed at the expense 

 of the spiny rays. 



