of certain Fishes of the Ganges. 39 



the foramen, and admits of being projected into it, to such an 

 extent as almost to touch its fellow of the opposite side, when 

 both mallei are at the same time gently depressed with the 

 finger, upon the incudes. The anterior portion of the malleus, 

 and the incus with its tendon, as far as its attachment to the 

 stapes, are inclosed in a tendinous sheath, containing a quantity 

 of gelatinous fluid : they have no muscles attached to them, 

 and it is probable, therefore, that the slight motion which the 

 malleus enjoys, through the medium of its articulation with 

 the vertebra, is entirely regulated by the external coat of the 

 air-bladder. 



The air-bladder of the Pimelodus Gagora, Pimelodus Bag- 

 haria, Silurus Singio, and Macropteronotus Magur, is placed 

 behind the head, close to its articulation with the first vertebra, 

 and in this situation is connected with the ossicula auditus, 

 which are conspicuous, and present the same relative position 

 as those of the Silurus Boalis. 



In the P. Gagora there are two air-bladders lodged, one on 

 each side, in an osseous cup attached by a narrow neck to the 

 body of the first vertebra, close to its junction with the cra- 

 nium. The mouth of each of these cups is covered over by 

 the common integuments, which ai-e at this part extremely thin, 

 and adhere to the surface of the subjacent bladder, presenting, 

 when the latter is distended with air, an external elastic tumour, 

 of an oval figure. The two air-bladders., which have no com- 

 munication with each other, or with the alimentary canal, 

 apparently derive their supply of air from a vascular tissue, 

 placed between the two cups where they are attached to the 

 spine : the external coat is of a thin texture, and argentine 

 colour, and has a layer of fine adipose substance interposed be- 

 tween it and the internal surface of the cup. 



The P. Bagharia has also two air-bladders, which closely rc- 

 seinblethe former in the argentine tendinoustexturc of the exter- 

 nal coat, and in having no communication with each other, or 

 with the alimentary canal. They are situate, one on each side 

 of the body, in a deep groove or furrow of the consolidated 

 transverse proccwei of the cervical vertebra', and are extreme- 

 ly small, in proportion to the bulk of the fish ; each of them, 

 in an individual weighing tin pounds, not exceeding a large 



