ICHTHYOLOGY. 



235 



Selachii. 



Chondrop- scribed by Russel, R. suttivara ; and one from Brazil, R. 

 terygii. electricus, Marc, whicli, as its specific name implies, has 

 been said to possess some of tlie properties of the Torpedo. 



Genus Rhina, Sch. This subdivision has a short, 

 rounded muzzle ; in other respects it is like the last nam- 

 ed. The species is R. anci/lostomus of Bloch. 



Genus Torpedo, Dum. This subdivision is short, and 

 rather fleshy. The body appears a nearly circular disk, 

 the anterior edge being composed of two projections of 

 the muzzle, which stretch sidewise, and unite with the 

 pectorals. The space between these last and the head is 

 entirely filled with the very extraordinary electric appara- 

 tus first accurately described by John Hunter. It consists 

 of irregular columns, varying from one and a half inch to 

 one fourth of an inch in length by 0-2 broad. They are 

 irregular hexagons or pentagons, reaching from surface to 

 surface of the fish, and forming (in that dissected by 

 Hunter) an electric organ five inches long, varying in 

 breadth from three to about one and a half inches. Their 

 number on both sides is about 940 in a small fish ; but in 

 a large one there were 2364. Their coats are thin and 

 transparent ; they are horizontally divided by thin parti- 

 tions, so numerous that one inch of these columns con- 

 tained 150 dissepiments filled with fluid. This curious 

 apparatus is supplied with numerous nerves from the 

 eighth pair. The columns are firmly united by cellular 

 substance. When the skin covering this apparatus is 

 touched, the person receives a violent shock at each con- 

 tact ; and it is probable that in this way the species stuns 

 its prey. The animal can give the shock at pleasure ; but 

 if often reiterated, the shocks are weakened, until the ner- 

 vous energy of the fish is recruited by rest. This animal 

 electricity is conducted and intercepted by the same sub- 

 stances that conduct and intercept ordinary artificial elec- 

 tricity. Wehere figure T.Ba7icrqftii. ^PlateCCCVll.fig.S. 



Several species occur in Europe, which Linna2us con- 

 founded together under the title of Raia torpedo. We 

 have Torpedo naske, distinguished by having no fleshy 

 dentations at the edges of its temporal apertures ; its dor- 

 sal spots vary from one to five : Torp. Galvmiii has seven 

 dentations round its air-holes, and is of an uniform brown, 

 sometimes marbled or spotted with darker tints : Torp. 

 marmorata is another Mediterranean species, described by 

 Risso. We know several foreign species, such as Torp. 

 temeree and Torp. nalatemeree of Russel, Torp. timlei? of 

 Bloch. 



Genus Raia, properly so called. Has a rhomboidal 

 body united to a slender tail, which has near its extremi- 

 ty two small dorsals, with, in some instances, a vestige of 

 a caudal fin. The teeth are small, and disposed in a 

 quincunx arrangement on the jaws. Several species in- 

 habit the European seas, some of which are yet indiffer- 

 ently distinguished by naturalists. As articles of diet, 

 some of them are frequently used ; and though seldom 

 seen at the tables of the rich, they are by no means des- 

 picable food, especially their pectorals. 



Raia clavata, or thornback, is a common species, dis- 

 tinguished by the roughness of its back, and the strong os- 

 seous oval plates, each furnished with a curved prickle, that 

 are irregularly scattered on both its surfaces. These plates 

 are variable in number, and therefore do not afford any 

 diagnostic character. 



Raia rubus, rough ray. There is much confusion among 

 Ichthyologists respecting this and the next species. Cu- 

 vier seems to think that the Balls of Pennant and Rubus 

 of Lacepede are the same ; but Rubus of Pennant and 

 Willughijy is certainly different from the skate, and dis- 

 tinguished from the last by its less pointed nose and the 

 greater length of the tail, and is more thickly studded with 

 small spines, not only on the back, but on the fins and 

 belly, which are equally rough with the back. There are 



Selachii. 



three rows of large spines down the tail, the surface of Chondrop. 

 which is irregularly beset with small prickles. It is to this i^'.^K^.'- 

 species that we confine the name of R. rubus. It is less 

 common than R. batis, and is a much smaller fish. Found 

 among the Hebrides. 



R. batis, the skate. One of the thinnest and broadest of 

 the tribe ; but sometimes growing to an immense size, and 

 weighing 200 pounds. The nose, though not very long, 

 is pointed. Sometimes the surface of the back is marbled 

 with dusky and white. Along the tail is one row of spines ; 

 a few are irregularly dispersed on the sides of the tail, and 

 the fins of the males have many small spines. 



The spring is their season of love ; and when coupling, 

 both may be drawn into the boat, though one only has 

 taken the bait. The male holders appear to be true organs 

 of penetration, as we have been assured by fishermen. The 

 eggs have the form of coriaceous parallelograms, and are 

 vulgarly with us termed purses, which the females begin to 

 cast in May, and continue to perfect and cast till Septem- 

 ber. This species is often eaten, as well as the thornback, 

 both in the greatest perfection in spring. 



R. oxyriiichus, the sharp-nosed ray. We do not agree 

 with Cuvier in confounding this with R. batis. The form 

 of the nose is much longer and narrower ; the body much 

 smoother than any species we have mentioned, though there 

 are triple rows of small spines along the tail. A single row 

 of small spines runs down its back, and a few are scattered 

 about the eyes. The teeth too, in this species, differ from 

 those of the skate, being bent inward, and less granular. It 

 is not inferior in size to the skate. Indeed specimens are 

 said to have been seen of the weight of 500 pounds. 



Some species of this division have a sort of membra- 

 nous expansion, like a fin elevated in the middle of the 

 back. This has been seen also in rays in other respects 

 resembling the skate ; but it is particularly conspicuous in 

 R. Cuvieri. To this division likewise belong R. undulata, 

 Lacej)., R. fultonica, R. marginata, R. miraletus, Ronde- 

 let, R. picta, R. alba, and others. 



Genus Trygon, Adans. Is characterised by having 

 the tail armed with a spine, finely serrated on both sides ; 

 and by the teeth, which are slender, and crowded in a quin- 

 cunx. Form of the disk obtuse ; some have the tail fleshy, 

 but in many it is very slender, and almost destitute of the 

 rudiment of a fin. Most of them have smooth bodies ; 

 their caudal spine long — a powerful weapon of offence and 

 of defence, which inflicts severe and dangerous wounds. 



R. pastinacea, Linn. ; sting ray. Is found on the Euro- 

 pean coasts. Some have a few prickles on the back ; it is 

 tuberculated in others. In some species the lower part of 

 the tail has a broad membrane, — others have a short tail 

 terminated by a fin. The principal species are, P. tuber- 

 culata; P. Wolga Tenkee, Russ. ; P. sephen, Forsk. ; P. Ges- 

 neri, Cuv. ; P. lymna, P. Jamaicensis, Cuv. ; P. cruciata, 

 Lacep. ; P. kunsua, Russ. 



Genus Anacanthus, Ehrenb. Has a general resem- 

 blance to Pastinaca, but is destitute of the spine and anal 

 fin. This sub-genus is formed from the description receiv- 

 ed of the large shagreen ray of the Red Sea, in which 

 the grains are stellular. 



R. orbicularis, Bl. belongs to this division. 

 Genus Myliobatis, Dumer. This sub-genus has the 

 head projecting beyond the pectorals altogether ; and these 

 fins have a greater proportional breadth than in the other 

 rays, which gives these animals no small resemblance to a 

 bird with its wings extended ; but their name is derived 

 from the millstone-like form of their broad flat teeth, 

 planted on their jaws like the stones of a pavement : their 

 tail, long, slender, and tapering to a point, is armed, as 

 in Pastinaca, with a strong spine, toothed on both sides, 

 and is furnished, just above the spine, with a small dorsal 

 fin. In some instances there are two or more such spines. 



