522 PISCES—SUB-CLASS IV.—ELASMOBRANCHII. 



violently, and thus inflict severe wounds. In comparison with the electric 

 rays — in which the width of the disc seldom exceeds from two to three feet — 

 these fishes are giants, their length being at times as much as fifteen feet. 

 The tropical devil-fishes forming the genera Dicerobatis and Cephaloptera are, 

 however, still more gigantic, some examples measuring nearly twenty feet 

 across the disc, and weighing considerably more than a thousand pounds. In 

 Dicerobatis the truncated muzzle is armed with a formidable pair of horns, 

 the mouth is inferior, and has both its jaws furnished with teeth. On the 

 other hand, in Cephaloptera, the position of the mouth is terminal, and there 

 are teeth only in the lower jaw. Of these ungainly monsters, Mr. S. Ward, 

 in a letter quoted by Dr. Percival Wright, describes his experiences in the 

 Seychelles as follows : — " Coming home, we passed close to an enormous 

 diable-de-mer floating quietly about. We changed from the pirogue to the 

 whale-boat, which I had scientifically fitted up for the grosses poissdns, and 

 went alongside of him, driving a regular whale-harpoon right through his 

 body. The way he towed the whaler was beautiful, but we would not give 

 him an inch of line, and he had to succumb to a rather protracted lancing. 

 His size will give you an idea of his strength in the water — forty-two feet in 

 circumference. We got him awash on the beach, but the united strength of 

 ten men could not get him an inch farther, so we were obliged to leave him 

 there. By this time the sharks will not have left much of him ; they have 

 not had such a meal for a long time. The fishermen say that, when alive, 

 the sharks do not molest the diable-de-mer, whose offensive weapons consist 

 of their enormous flexible sides (one can hardly call them tins) with which 

 they can beat almost any shark to death. Asa rule, when harpooned, they 

 endeavour, like other rays, to bury themselves in the sand, and if they 

 succeed in doing this, no line can ever haul them out of it — their flat bodies 

 act on the principle of an enormous sucker. Another curious fact about 

 them is that when harpooned, they swim sideways, edge-on, in order to avoid 

 exposing too broad a surface to the enemy. They never do this unless 

 harpooned." Other genera are Aetobatis and Rhinoptera, both distinguished 

 by the dentition and the position and form of the fins. Whereas the former 

 of these has but a single species, the latter possesses several. 



The last existing representatives of the Elasmobranchii are the formidable 

 and dreaded sting-rays, which are typified by the genus Trygon, but also 



include Pteroplatea, Urogymnus, and Urolophvs. In species 



Family the typical genus is very numerous, some of these having a 



Trygonidie. very wide geographical range. They are mostly tropical, 



and attain their maximum development in the Atlantic Ocean 

 and the Indian seas. It is remarkable that certain species inhabiting the 

 eastern districts of Tropical America have become accustomed to a fresh- 

 water existence, and are now restricted to certain inland lakes. All these 

 fishes are distinguished by the excessive development of the fore-part of the 

 pectoral fins, which are so extended as to encircle the muzzle, and thus com- 

 plete the disc. The whip-like tail is distinctly marked oS from the body, 

 and generally bears a poisonous serrated spine ; and in many kinds the 

 median fins — which are never large — are replaced by similar spines. These 

 armed rays are some of the most dangerous of all fishes. 



