CHONDROPTERYGII. 639 



in general, but are so tame as to suffer themselves to be 

 touched lying motionless on the surface of the water, as if to 

 sun themselves, whence they are called basking sharks. A 

 large fish will yield eight barrels of oil. When struck with the 

 harpoon and wounded, they fling up the tail, and plunge 

 headlong to the bottom, coiling the harpoon rope round them, 

 and attempting to disengage themselves from it by rolling on 

 the ground. They then swim away with such rapidity and 

 violence, that they have been known to tow a vessel of 

 seventy tons burthen against a fresh gale, and they will 

 employ the fishers for twelve, and sometimes twenty-four 

 hours, to subdue them. 



The Squalus centrina of Lin., Centrina vulgaris, Cuv., 

 and Squale humantin of Lacepede, is very remarkable in its 

 appearance, having the spines in the dorsal fin, which distin- 

 guish it generally in the modern system, one directed forward 

 and the other backward. Its shape is a subtriangular prism, 

 the belly forming one of the three sides. It inhabits the 

 Atlantic and the Mediterranean, but its flesh is so hard and 

 stringy, that it is almost impossible to eat it. It lives at 

 the bottom of the water, in the sand or mud, and is hence 

 called by fishermen the sea-hog. 



No animal is perhaps more singular or remarkable, especially 

 of the larger sort, than the Squalus zygcena of Lin., the ham- 

 mer-headed shark, the type of the genus Zygcena of our 

 author. The head is flatted horizontally, truncated in front, 

 with each side elongated into a branch, like a double-headed 

 hammer, or the letter T. The eyes are large, prominent, and 

 lodged at the extremities of these branches of the head, which 

 are also pierced by the nostrils at their anterior edge. The 

 opening of the mouth is semicircular, the teeth are large, 

 sharp, indented on each side, with three rows in each jaw. 



This fish inhabits most of the southern seas, is of a gray 

 colour, with the head nearly black, the eyes are yellow, with 



