( 18 ) 



AiUiclithys; 17, Eutropiichthys ; 18, Sisor ; 19, Gagata ; 20, 

 Ilemipimelodus ; 21, Bagarius ; 22, Pseudecheneis ; 23, 6r/#p- 

 tosternum ; 24, Amblyceps, and 25, Exostoma. Out of the 

 foregoing 25 genera, some are residents in waters of the 

 plains, also in rivers of the hills with or without Alpine 

 sources. A nongst the 17 resident solely in waters of the 

 plains, and not extending their range into hilly regions, we 

 find that in eight, Nos. 2, 3, 4, 5, 6, 7, 8, 9, the air-vessel 

 is free in the abdominal cavity and not enclosed in bone ; 

 whilst in ten, Nos. 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, it is 

 more or less so enclosed. Amongst those residing in 

 rivers of the plains, and extending their range into those 

 of the hills which have or are destitute of Alpine sources, we 

 perceive four, Nos. 22, 23, 24, 25, which are found in the 

 waters of the plains as well as in the hill rivers with Alpine 

 sources ; all have their air-vessels enclosed in bone, the 

 two first have a thoracic adhesive apparatus, whilst the last 

 three have representatives in the next division, and Nos 22 

 and 23 are furnished with a thoracic adhesive apparatus. 

 The remaining three genera, Nos. 1, 10, 11, are found in 

 rivers of the plains, and also in those of hills destitute of 

 Alpine sources, whilst in none is the air-vessel enclosed 

 in bone. Prom the foregoing it appears that the majority 

 of the genera of the Indian fresh-water siluroids have their 

 air-vessel enclosed in bone, whilst it is not so enclosed in any 

 of the marine forms ; that amongst the siluroids of hilly 

 regions, those which ascend rivers having Alpine sources 

 have the air-vessel enclosed in bone : whilst those which 

 ascend rivers not snow-fed do not appear of necessity to 

 have their air-vessel thus protected. 



XXXI. The fresh-water siluroids may be divided 

 into those of the hills and those of 



Siluroids of hills and plains. ... 7 



the plains ; the former, or those oi the 



hills, being small and often possessing a thoracic adhesive 

 apparatus to enable them to adhere to rocks, and prevent 

 their being carried away by descending torrents. The silu- 

 roids of the plains are very numerous, existing in almost 

 every piece of fresh-water, whilst the larger rivers contain 

 some, as the Pangasius Buchanani, Wallago attu, Silundia 

 Gangetica, and Sagarins Yarrellii, which attain to several feet 

 in length : in fact, up country, as in the upper portions of the 

 Jumna and Ganges and in the irrigation canals, where they 

 find abundance of food, and consequently grow to a very great 

 size, they are erroneously termed "sharks." None of these 

 siluroids possess any adhesive apparatus unless they are also 



