2I g - THE THORNBACK SKATE. 



the best researches, that the growth of this organ is produced, not by the increase of 

 each column but by a continual addition to their number. A vast amount of blood- 

 vessels pass through the electric organ, and it is permeated with nerves in every 

 direction. 



How the electrical effect is produced is a very deep mystery. In fact, we know 

 scarcely aught of this marvellous power, save the knowledge that it pervades all nature, 

 and even in its external manifestations is one of the most ethereal and most potent of 

 the second means through which the will of the Creator guides His universe. That 

 the same electrical principle exists in all animals is familiarly known, and also that it 

 is far more intense in some individuals than in others of the same species. It is known 

 that the contact of two different kinds of flesh, such as the muscle of a fish and an ox, 

 both newly killed, will produce similar effects ; and that it exists so largely in human 

 beings, that no two individuals can place themselves on isolated stools, and join their 

 hands, without emitting so much electricity by that slight contact, that the instrument 

 will record its presence. But the origin of this wonderful power eludes our mental grasp 

 like the receding waters of the mirage, and the increase of our knowledge serves but to 

 betray the extent of our ignorance. 



I cannot but think that this subtle and potent emanation, which is able to strike the 

 victim through an intervening space of the fluid common to both aggressor and sufferer, 

 has some affinity with the still more subtle and equally mysterious influence by which 

 certain of the serpent race are enabled to paralyze or attract the creatures which they 

 could not secure by actual contact. It may possibly be that the electric powers of the 

 Torpedo, which need water or some other conducting substance for their exercise, are, 

 after all, but a more concentrated and palpable manifestation of that force, which en- 

 ables the rattlesnake to arrest an animal not in physical contact with itself, the pointed 

 finger to lay a bird motionless on its back until released by a sudden sound or touch, 

 and one human being to influence his fellow without the use of words, and to attract 

 or repel him by an irresistible though invisible agency. 



It is rather remarkable that even the Torpedo, gifted with such puissant arms, deal- 

 ing pain and death around at will, should find at all events one foe insensible to the 

 electric stroke, and perhaps even needing its exciting influence to preserve it in health. 

 This is a parasitic creature, termed scientifically the Branchellion, which clings to the 

 Torpedo and feeds upon its juices, quite indifferent to all the shocks which its victim 

 dispenses. It generally measures from an inch to an inch and a half in length. 



This fish is found in the Mediterranean, and the Indian and Pacific Oceans, and oc- 

 casionally off the Cape, and has now and then been captured on our coasts. Happily, 

 the Torpedo does not attain a very great size, one of the largest specimens being about 

 four feet long, and weighing sixty or seventy pounds. 



THE Rays are well represented in England by several large and curious species. 

 One of the commonest examples is the THORNBACK SKATE or RAY, so called from the 

 large number of thorny projections which are scattered over its back and especially 

 along the spine. This species is represented by the upper figure in the illustration. 



The Thornback is one of our common Rays, and is taken plentifully on the shores 

 of England, Scotland, and Ireland. As is the case with many of the same genus, the 

 flesh is considered rather good, and is eaten both when fresh and when salted for con- 

 sumption during stormy weather. Autumn and winter are the best seasons for pro- 

 curing this fish, as the flesh is then firm and white, while during the rest of the year it is 

 rather liable to become flabby. Thornbacks taken in November are thought to be the best. 



This species, like the rest of the Rays, feeds on Crustacea, flat-fish, and molluscs, and 

 as many of these creatures possess very hard shells, the Rays are furnished with a 

 crushing mill of teeth, which roll on each other in such a way that even the stony shell 

 of a crab is broken up under the pressure. It is notable that the teeth differ in the two 

 sexes when adult. Those of the female are flat on the top, but those of the male throw 

 out a strong angular projection, which is so arranged that the projections of one jaw 

 exactly fit into the interstices of the other, and the roller-like arrays of teeth bear a won- 

 derful resemblance to the well-known clod-crushing machine. 



