34 Mr Taylor on the Respiratory Organs and Air-bladder 



kidney : they are composed of a smooth semitransparent sub- 

 stance, apparently possessing the properties of the arterial tis- 

 sue, and are of a deep red colour, their external surface being 

 extensively covered by the minute branches of the branchial 

 artery. The aex'ated blood appears to be imbibed from the 

 extremities of these branches, through innumerable villi in the 

 parietes of the respiratory ramifications into their internal ca- 

 nals, 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. 



Coins Cobojius, and Trichopodus Colisa. Each of the bran- 

 chial 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 rudiment of 

 that structure. The supernumerary organ of each side lodged 

 in a cavity, 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 in- 

 ternal side of the operculum. It consists of several broad but 

 very thin cartilaginous plates of a convoluted figure, intimately 

 connected at their bases, and so arranged as to present the ap- 

 pearance of a rosette. The branchial artery and aortic vessels 

 are ramified upon a thin membrane, reflected from the laminae 

 over the surface of this foliated organ, giving it a deep red colour. 



Oph'wcephalus Gachua. The branchial arches of this spe- 

 cies have also very short laminae. 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 plates, and consists of a thick solid tissue, having a curled 

 margin, not unlike that of the common species of alga, or sea- 

 weed. The branchial artery having given oil" branches to the 

 lamina' of the arches, runs for a short distance in a canal of 



