6)5 Proceedings of Philosophical Societies. [July, 



muscular, and there is a particular muscle connected with the 

 valves, which Sir Everard conceives intended to impel the blood 

 more powerfully through the gills when the animal is at a great 

 depth under water ; for the pressure of the water will in that 

 case impede the circulation in the gills. It occurred to Sir 

 Everard that this impeded circulation might be compensated by 

 water at great depths containing more oxygen gas in solution 

 than near the surface; but water being taken up from the bottom 

 of a deep well, and examined, was found to contain no more 

 than water at the surface. It may be remarked here, that 

 this trial was scarcely of such a nature as to be decisive. Well 

 water, however deep, is nothing else than rain water which has 

 made its way through the earth to the bottom of the well ; and 

 all of it having been equally exposed to the air when falling in 

 the state of rain ought to contain the same portion of air. The 

 water examined ought to have been taken from the bottom of 

 the sea; but it is not likely that any perceptible difference would 

 have been found. Indeed, the experiment has been already 

 made by Biot, who examined sea water taken up at the depth of 

 437 fathoms, and found the proportion of oxygen gas in it the 

 same as at the surface. (Mem. d' Arcueit. i. 2/3.) But the 

 swimming bladder being filled with oxygen gas in those fishes 

 that live at great depths, this in all probability is intended to 

 answer some such purpose. 



Sir Everard compared the heart of the squalus with that of 

 several other animals. The squalus has no cerebrum, but only 

 cerebellum. The cavity in which the semicircular canals of the 

 ear is placed is uncommonly large. The lens of the eye is 

 globular, and half sunk in the vitreous humour, which is very 

 firm, and lodged, as usual, in separate cells. The retina is very 

 thin. The cornea consists of three coats. 



LINN-flEAN SOCIETY. 



The Society met upon Tuesday the 1st, and Tuesday the 15th 

 of June. Both meetings were occupied in hearing read a paper 

 by Col. Hardwicke, on the bats in the British dominions in 

 India. He described and exhibited figures of 1 1 species, most 

 of which inhabit trees, and live on fruits. The most remarkable 

 of these is a very large species, having the aspect of a wolf, and 

 of such a size that, from tip to tip, the wings extend 3 feet 

 8-1- inches. This species the Colonel considers either as the 

 vain pyre of Linnaeus, or as nearly allied to it. It lives on fruits, 

 and is considered by the Indians as quite harmless. The Colonel 

 found that it would eat raw flesh when hungry ; but that it pre- 

 ferred fruits. The stories of its sucking the blood of living 

 animals he considers as quite unfounded. 



The Society adjourned till the 2d of November. 



