1086 



SCANDINAVIAN FISHES. 



PLAGIOSTOMI BATOIDEI". 



/?rt.se of the pectoral fins extended hachvards aJoriff the sides of the bodii and fonrards alomi those of the head, 



ahore the fire hravehial apertnres. Tail slender, terete {Khrp-Jike^' or depressed. No anal fin. 



All the rertical fins helong to the tail. 



Tlie most iinportiint distinctions between the Rays 

 and Shai'ks we have already mentioned in the intro- 

 duction to the Elasmobranchs. They are bound up with 

 the diftcrent habits of tliese fishes. Nearly all the Rays 

 are ground-swimmers and live in the same manner as 

 the Flounder-fishes, only seldom attempting rapid ex- 

 cursions or movements in the water. The above-men- 

 tioned intermediate forms — the well-known Saw-fishes 

 (Prisfis) and their nearest relatives, without a saw, the 

 Bhinohatidee, a family common principally in Indian 

 waters — therefore apjjroach, in their way of life as 

 well, the transition to tlie .Sharks. 



Among the vital capacities of the Rays one, namely 

 the power of giving electric shocks, possesses a special 

 interest. Not only is this facultj- a rare phenomenon 

 in the whole animal kingdom and the peculiar property 

 of fislies — even among these it is shared, in a singular 

 and liitherto unexplained manner, by representatives of 

 widely separated orders and families. At least two 

 Teleosteous families'' are endowed with this power, and 

 a third" possesses it in so slight a degree that doubt 

 is still felt whetlier this family should be included 

 among the electric fishes or not; but none of these 

 Teleosts is so nearly connected with the Scandinavian 

 fauna as to have induced us to describe its faculties. 



That electricity is really present both in muscles 

 and nerves, or, to express ourselves more cautiously, 

 that at least under certain circumstances electricity 

 may be stored in nuiscles and nerves, has long been 

 known; })ut nowhere has this electricity such an opjior- 

 tunit}' of accumulating as in certain fishes. The earliest 

 and best known among these fishes are the Electric 

 EaiiK. Their family, the Torpedinida-, is fairly rich 

 in forms: about 20 species, distributed among 6 genera, 

 have been described witli varying accuracy from the 

 tropical and temperate seas. Three of them — Torpedo 

 nohiliana, Torp. ocellata (narce), and Torp. marmorata — 



live in the ]\Ieditcrrant'an and the adjoining parts of 

 the Atlantic, the last-mentioned species being besides 

 an inhabitant of the Indian Ocean. 



The power possessed by the Electric Rays of ac- 

 cumulating electricity in their organs and voluntarily 

 discharging these at need has been known at least since 

 the time of Aristotle and Theopheastus; and Roman 

 physicians, ^\'hen Galen lived, if not before, employed 

 these Raj's in the treatment of gout and nervous dis- 

 eases. In recent times this electricity has been more 

 minutely studied, and has been found to be identical 

 in its effects with other electricity. It has the same 

 influence on the magnetic needle, it can decompose 

 chemical compounds, and it emits the electric spark. 

 When the Neapolitan fishermen have drawn their seines 

 ashore, it is usually, according to Owen, their first 

 care to pour a bucket of water over the catch. If the 

 net contains an Electric Ray, its presence is at once 

 betrayed by the shock transmitted along the stream of 

 water to the hand holding the bucket. To handle a 

 live Electric Ray is unpleasant enough, for the arm at 

 least is paralysed by the shock for a long while. 



Like the still more powerful Electric Eel — which 

 is not an Eel, though it has the external appearance 

 of one, but rather a Sheatfish, an inhabitant of fresh 

 water in tropical South America — these Rays employ 

 their electric power both to kill or at least to stun 

 their prey and to defend themselves against their ene- 

 mies. The other electric fishes known to us are far 

 inferior in their cajjacity of accumulating electricity, 

 and probabl)' have recourse to this faculty in defence 

 alone. Other fishes again scarcely have the power of 

 giving appi'eciable electric shocks, but possess true elec- 

 tric organs, which on account of their feebleness have 

 been called pseudoelectric. Such organs appear in se- 

 veral of our common Rays. Their strength is not 

 great, and it has seldom been observed; but in 1888 



" Gr. (idvog, Ray. 



'• Fain. Gijmnotida: (Elcciric Eels) iiml Ihe subfamily MalapteritriiKi; of llie great Slienlfish faiiiilv 



'" Fain. Morinyrida'. 



