Page:Proceedings of the Royal Society of London Vol 1.djvu/353

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Half way between the eye and the gills was an orifice and canal leading to the mouth. The gills five in number on each side.

The fins, and also their situation, are particularly described.

Adjacent to the anal fins are placed two holders for the purpose of grasping the female, terminated by a flat, sharp, bony process five inches long, which moves on a joint, and is, in fact, the termination of a series of parts corresponding to the pelvis, femur, tibia, and foot of quadrupeds.

The pectoral fins also correspond in some measure to the anterior extremities, and are connected by cartilages, which answer the same purposes as the scapulae and sternum of quadrupeds.

The heart was not larger than that of a bullock, with three valves at the origin of the pulmonary artery, three at the entrance of the aorta, and also two sets more, of three each, in the course of the artery, at a short distance from each other.

The stomach contained several pails full of pebbles, a quantity of mucus, and a small portion of substance that looked like the spawn of the oyster.

Beside the cardiac and pyloric portions of the stomach observable in other sharks, there was a globular cavity communicating with the pyloric portion by a very small orifice, and by another, equally small, with the intestine. '

The liver of this fish yielded about three hogsheads of oil. The vessels of the liver were large enough to admit a man’s arm. The bile is conveyed direct to the intfitine by twelve hepatic ducts. for there is no gall-bladder.

Although the Squalus here described resembles, in many respects, the tribe of Sharks, it is observed to difi'er essentially in the form of its stomach, which is intermediate between that of the shark and whale.

In the modes of generation, also, as well as in the stomachs, a. series of gradations may be observed from whales through the squa- lus, sharks, rays, and skates, to the proper fishes; but this inquiry will form the subject of a future communication.

Mr. Home closes the present account by such particulars as he could collect concerning a large fish thrown ashore on one of the Orkneys, and described as a sea-snake by those who had seen it half putrid and half devoured by sea-fowl ; but it was ascertained by Mr. Home to be in reality another specimen of the same Squalus as that above described.

On an Improvement in the M anner Qf dividing astronomical Instruments. By Henry Cavendish, Esq. F.R.S. Read May 18, 1809. [Phil. 'I’rans. 1809, p. 221.]

The use of the common beam-compass for dividing having been justly objected to, on account of the danger of bruising the divisions which have been made, by replacing the points of the compass into