THE MAYS. 37 



the middle of the back ; there are half-circles of spines like eyebrows behind the eyes, which are 

 placed on the top of the head, and are covered with skin, excspt round the pupils. Their colour is sandy- 

 grey. There are about a hundred and twenty joints in the vertebral column ; none of the vertebras 

 are united together, as among Rays. The arches over the spinal cord are broad plates, which cover 

 the bodies of two vertebra?. The teeth are arranged at intervals, with four or five successional 

 teeth behind the outermost one. This Shark was well known to the Greeks, who used its skin in 

 polishing wood and ivory. Its flesh was also valued for food, and is described as firm and 

 nourishing. It is still eaten in the north of France. 



The males of this species, like most other Sharks, are furnished with prehensile appendages 

 termed " claspers," but they do not here attain a large size. The species is widely distributed in 

 temperate and tropical seas, being found in the Atlantic and on both sides of the Pacific. 



FAMILY IX. PRISTIOPHORID^E. 



This, the ninth and last of Dr. Giinther's families of Sharks, also only includes one genus 

 Pristiophorus characterised by having the cartilage of the fore-part of the head prolonged 

 into a long flat plate, which is armed on each edge with a series of teeth, so as to resemble a saw. 

 There are also numerous rows of teeth in the upper jaw, sometimes as many as fifty-eight. The 

 nostrils are on the under side of the head. The scales are minute and keeled, and they more or 

 less completely cover the dorsal and pectoral fins. The body is somewhat depressed ; but the gill- 

 openings are lateral, while in the other Saw-fishes of the next family they are on the under side of 

 the body. The species range from Japan to Tasmania, and sometimes reach a length of five feet. 



The abundance of Sharks on the coasts of India appears to depend upon the presence of the 

 Oil Sardine (Clupea scombrina"), so that in some years, when these fishes are rare, or scarcely visit the 

 coasts, Sharks are also comparatively scarce. They have for many years been sought for for the sake 

 of their livers, which are used for the manufacture of medicinal oil. The livers are equally good at 

 any season of the year, but while small livers yield one-third of their weight of oil, the large ones 

 yield one-half their weight of oil. The best have a pinkish colour, and are firm. Those used in the 

 manufactui-e vary in weight from 40 Ibs. to 290 Ibs. The Sharks are captured with baits of putrid beef or 

 porpoise flesh, which are put on the hook and attached to a chain. The fishing is carried on in deep, 

 water, between four o'clock in the morning and sunset. The process of manufacture of the oil is- 

 comparatively simple ; the livers have to be received at the factory within six hours of the death of 

 the fish ; the veins are slit up and the gall-bladder removed, and the gland is washed until it no longer 

 discolours the water. It is then cut up into pieces which weigh about 4 Ibs. each, placed in an 

 earthen vessel and covered with about an inch and a-half of water. The vessel is then heated over 

 a slow fire for about a quarter of an hour, till it reaches a temperature of 130 Fahr. It is then, 

 stirred up, and as froth begins to rise the vessel is cooled on sand. The oil floats, and is skimmed, 

 off with a ladle formed from half a cocoa-nut shell attached to a bamboo handle. This rough oil 

 is strained through flannel, and then allowed to stand for three or four days, when it is again strained 

 through layers of long cloth, satin-cloth, and flannel, and again stands for a fortnight or three weeks. 

 The straining is then repeated. In all there are six strainings, the last being through cloth and 

 filtering-paper direct into the bottles in which it is stored. This oil has a light straw colour, and 

 closely resembles cod-liver oil. The cost of its manufacture, however, has of late increased so much 

 that the Indian Government, which formerly carried on the industry at Calicut, has found it less 

 expensive to import cod-liver oil from Europe. 



SUB-ORDER II BATOIDEI (RAYS). 



All the Rays have a depressed flattened body, which is expanded by the pectoral fins into a 

 more or less rhomboid or ovate form, usually terminated by a slender tail. Many species have the 

 snout pointed, though tlm character is by no means universal. The gills always open on the under 

 side of the body, and are always five in number. They communicate with spiracles, which open on 

 the head behind the eyes, and supply the gills with water while the animal lies on the ground. These 

 spiracles can be closed voluntarily. It has been estimated by Monro that, owing to the numerous 

 foldings of the gill-surface, the entire area of respiratory tissue is equal to the whole external surface 



