Mr Taylor on the respiratory organs and Air-bladder, cj-c. 33 



obtain a similar formula. It will be seen, that, if an arch of 

 10° elevation and 115° extent be 108 miles high, we must see 

 about 850 miles of its inner edge ; and a much greater length 

 of its outer edge ; and we may entertain a hope, that, being 

 on such a scale, something important may be learned on the 

 electro-magnetic theory of the earth, by comparing the calcu- 

 lated curvature with the various theories. 



Smedley Hall, Feb. \5th 1831. 



Art. IV. — On the Respiratory Organs and Air-Bladder of 

 certain Fishes of the Ganges. Jty J. Taylok, Esq. * 



Among the peculiarities of internal structure in the fishes of 

 the Ganges, the most remarkable, in a physiological point of 

 view, are those connected with the organs of respiration and 

 the air-bladder, in certain species of the genera Ophiocephalus, 

 Bola, Coins, Trichopodus, Macropteronotus, Pimelodus, Silu- 

 rus, Mystus, and Clupanadon. 



The Macropteronotus Magur, Coins Cobojius, Trichopodus 

 Colisa, Ophiocephalus Gachua, and Silurus Singio, present, in 

 addition to the usual number of gills observed in osseous fishes, 

 certain respiratory organs, which admit, it would seem from 

 the tenacity of life possessed by these species, of a higher de- 

 gree of oxygenation of the blood than is effected by means of 

 common branchiae. 



Macropteronotus Magur. This species (the Silurus Batra- 

 chus of Bloch) possesses, in a deep cavity on each side of the 

 head, two arborescent branchiae similar to those discovered by 

 M. Geoffroy, in the Silurus Anguillaris of the Nile. These 

 organs supply the place of the superior or cranial limbs of the 

 two middle arches, and consist of two vascular trunks, that 

 spread out into numerous small branches, resembling a tree 

 destitute of foliage, or rather a corroded preparation of the 



* Mr Taylor has been so kind as to transmit us a cony of this papw 

 previous to its publication in India, and has accompanied it with a series 

 of beautiful coloured drawings illustrative of his inquiries. We regret that 

 these cannot be given in a periodical work. — Bo. 



MEW SERIES, VOL. V. NO. I. JUL* 18131. C 



