GLEANINGS 
IN 
SCIENCE. 
JYo. 18. — June , 1830. 
I . — On the Respiratory Organs and Air Bladder of certain Fishes of 
the Ganges ; by J. Taylor, 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 , 
Bold, Coius, Trichopodus , Macropteronotus t Punelodus , Si turns, Mystus , and Clu- 
panadon . 
The Macropteronotus Magur , Coins Cobojius, Trichopodus Colisa, Ophiocephalus 
Gachua, and Silurus Singio, present, in addition to the usual number of gills ob- 
served in osseous fishes, certain respiratory organs, which admit, it would seem, 
from the tenacity of life possessed by these species, of a higher degree of oxygena- 
tion of the blood than is effected by means of common branchiae. 
Macropteronotus Magur • This species (the Silurus Batrachus of Bloch) possess- 
es, in a deep cavity on each side of the head, two arborescent branchi®, similar to 
those discovered by M. Geoffroy, in the Silurus Anguillans 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 kidney : they are composed of a smooth semi-transparent substance, appa- 
rently possessing the properties of the arterial tissue, and are of a deep red colour, 
their external surface being extensively covered by the minute branches of the 
branchial artery. The aerated blood appears to he imbibed from the extremities 
of these branches, through innumerable villi in the parietes of the respiratory 
ramifications into their internal canals, and thence flows into the small vessels 
that unite to form the aorta. Cuvier assigns to these organs, the double function 
of affording a surface for the oxygenation of the blood, and of acting as so many 
hearts for propelling it into the aorta. 
Coius Cobojius, and Trichopodus Colisa. Each of the branchial arches in these 
fishes, consists only of one osseous portion or limb, and is provided with very 
short cartilaginous laminae ; the fourth or posterior arch presenting merely a ru- 
diment of that structure. The supernumerary organ of each side lodged in a ca- 
vity, as in the M. Magur, and supported upon a broad stalk of cartilage, which is 
fixed above, by a tendinous process, to the side of the cranium, and below, to the 
ends of the first and second arches, is concealed from view, by a thin membrane 
that extends across from the bone corresponding to the clavicle and the superior 
extremities of the branchial arches, to the internal side of the operculum. It con- 
sists of several broad but very thin cartilaginous plates of a convoluted figure, 
intimately connected at their bases, and so arranged as to present the appearance 
of a rosette. The branchial artery and aortic vessels are ramified upon a thin mem- 
brane, reflected from the laminse over the surface of this foliated organ, giving it 
a deep red colour. 
Ophiocephalus Gachua. The branchial arches of this species have also very 
short lauiins. The supernumerary organ of each side is divided into two portions 
supported upon two broad osseous plates, one projecting from the internal side of 
the articular bone of the head, and connected with the cornu of the os hyoides ; 
the other, articulated with the anterior branchial arch, the superior limb of which is 
wanting. The substance composing the organ, is situate upon the edge of these 
