THE STING It AY. 43 



it is preserved by pressure, large stones being heaped over the fishes to squeeze out the juices of the 

 body, after which it is only necessary to secure the flesh from rain and moisture. The quantity taken 

 depends a good deal upon the bait ; the Pilchard and Herring always attract it, but it feeds on Crab? 

 and other Crustacea, and according to Yarrell also upon Flat-fish and Mollusca. A specimen three 

 feet two inches long was twenty-eight inches broad, and had the tail a foot and a half long. The 

 teeth are rather large, but, like the spines and asperities, differ in character in the female and male. 

 In the former all the teeth are flat, but in the latter the middle teeth are conically pointed. Nearly 

 allied to this species is the Raja, radiata, in which the large spines on the back attain greater dimen- 

 sions than in the Thornback, and rise from an expanded base ; the largest spines are in the middle 

 line of the back and tail, and above the eyes. The shoulder-girdle of the Thornbauk is a nearly perfect 

 girdle formed at the sides by the scapula and coracoid, with the ring completed by the epicoracoids 

 below, and the supra-scapular above, which latter bones abut against the spine of a neck vertebra. 



In Psammobatis, which frequents the southern coasts of South America, the disc is perfectly 

 circular and only five inches wide, the snout being very short. Each ventral fin. is divided into two 

 by a deep notch ; the anterior portion is covered by the pectoral fin. Each nostril has two nasal 

 valves. The tail is three inches and a half long. 



Platyrhina has a well-developed caudal fin, and is represented by two species from India and 

 China, which both have the disc nearly circular. 



FAMILY V. TBYGONID^, THE STING KAYS. 



The Sting Rays form a large family, about twenty-four species of the genus Trygon being 

 known, chiefly from tropical and sub-tropical seas, while the family includes, according to Dr. 

 Giinther, several nearly-allied genera, such as Urogymnus, Tseniura, Urolophus, and Pteroplatea. 

 The common Sting Ray,* like all the members of its genus, has the pectoral fins prolonged forward 

 so as to unite in front of the head, while the tail is armed in its middle portion with a sharp, 

 flattened, bony spine, serrated on both sides like a double-edged saw or harpoon. The spine projects 

 upward and backward, and has the serrations hardened by an outer dense layer, so as closely to 

 resemble tooth-structure. When the dart has become worn out, its attachment to the body is loosened, 

 and after being cast off another one grows in its place. Occasionally the new spine protrudes from 

 under the old one, which may be seven inches long in a fish measuring three feet. This fish was 

 well known to the ancients, and regarded with dread on account of the supposed poison of its. 

 spine. It lives on shallow, sandy ground, rarely takes the bait, and is commonly caught by accident, 

 in nets. The flesh, when laid bare by skinning, is more than usually red, and is said to have a. 

 rank flavour. The species is comparatively rare on the British coast, but has a remarkably wide- 

 range being found in the Gulf of Mexico and on the northern coasts of South America, in the Canary- 

 Isles, and on the shores of China and Japan. Trygon hystrix a species frequenting the Brazilian 

 coast was taken by Mi*. Bates, at Santarem, on the Amazons. Trygon tuberculata, a species which 

 has the tail twice as long as the body, ranges from Sydney to the tropical parts of the Atlantic, 

 and yet occurs in Lake Champlain. Trygon hastata, from New York, has the tail armed with two 

 spines placed at a distance from each other. Trygon rudis, from Old Calabar, has the body six 

 feet and a half broad, by four fest and a half long, while the tail measures fully six feet more. 

 Usually the plates which carry the teeth are straight, or but gently undulating, but in the Trygon 

 sepken, a species met with in the Indian Ocean and the Red Sea, the upper jaw is angularly bent, 

 and receives the lower jaw which is necessarily somewhat pointed within this concavity. Rarely 

 Trygons occur which have the body almost or entirely smooth, such as Trygon nuda. The longest- 

 tailed species is Trygon uarnak, which has the body three feet long, with a tail nine feet long. The 

 genus Taeniura is represented by six species, some of which are found in the East Indian seas, and 

 others in the fresh waters of tropical America, Tceninra motoro being found in the River Cuyaba, 

 in Brazil. Urolophus is a genus represented by five species, some of which are confined to the 

 Australian seas, and others, like Crolophus torpedimis, are found in the West Indies and on the 

 Pacific coast of Central America. In this genus the tail has a distinct terminal fin, with rays. 

 The genus Pteroplatea has the body at least twice as broad as long, and the tail very short and 



* Trygon pastinaca. 



