712 SURGEON F. DAY ON THE [DeC. 5, 



Plotosus canius, H. B. pi. 15. f. 44. 



Air-vessel of moderate size, placed transversely across the anterior 

 vertebrae. Its external fibrous coat is thick, whilst internally it is 

 divided by a longitudinal septum into two lateral cavities, which 

 communicate anteriorly by a large circular opening. 



Geographical distribution. — This genus contains marine and 

 estuary fishes ; but P. canius is sometimes captured in fresh water. 

 The genus has a very extensive range, being found in Africa, Asia, 

 through the Indian seas to the Malay archipelago, and even beyond it. 



Clarias magur, H. B. pi. 26. f. 45. 



Air-vessel tubular, placed transversely across the body of the an- 

 terior vertebrae, where it is entirely enclosed in a bony capsule. 

 This subject is remarked upon in Cuv. and Val. 



Geographical distribution. — The genus is found in Africa, India, 

 Ceylon, Burmah, throughout the Malay archipelago, even to be- 

 yond it. 



Saccobranchtjs fossilis, Bl. 



Silurus singio, H. B. pi. 37. f. 46. 



Air-vessel small and situated transversely across the body of the 

 anterior vertebrae, either extremity being enlarged, globular, and 

 enclosed in a bony capsule. Cuv. and Val. remark upon this. 



Geographical distribution. — The genus extends through India, 

 Ceylon, Burmah, and, according to Dr. Gunther, Cochin China. 



SlLUNDIA GANGETICA, Cuv. et Val. 



Pimelodus silondia, H. B. pi. 7. f. 50. 



Air-vessel small and placed transversely across the body of the 

 anterior vertebrae, where there is a groove to receive its posterior 

 surface ; anteriorly it has a thick, strong, fibrous covering. There 

 is a low osseous process from the vertebra, giving it protection late- 

 rally. The air-vessel itself consists of two small oval portions, having 

 a median connecting tube ; and this lateral part is surrounded by 

 osseous or strong fibrous walls. 



Geographical distribution. — Large rivers of India and Burmah. 



Ailia bengaliensis, Gray. 



Air-vessel as in the following genus. 



Geographical distribution. — Rivers of the plains of India (except 

 in Madras), extending to the upper portions of the Ganges and 

 Jumna, but not on to the hills; also Assam. 



Genus Ailiichthys, gen. nov. 



Differing from Ailia in that the ventral fins are entirely absent. 



Geographical distribution. — The Jumna, and southern rivers in 

 the Punjaub that are tributaries of the Indus, but not those on the 

 hills. 



