FISHES. 



539 



change its position a rapid and sudden stroke of this formidable 

 weapon, armed with hooked spines on its upper surface, arrests its 

 victim by wounding or killing it, without disturbing the mud or sea- 

 weed by which it is covered. This species sometimes attains a very 

 considerable size, and its flesh is firm and nourishing ; but the larger 

 specimens rarely approach inhabited shores, even when the female 

 desires to lay her eggs. These eggs have a very singular shape, 

 differing from almost every other fish, and particularly from those of 

 all other cartilaginous fishes. They are quadrangular, a little flat, 

 each of the four corners terminating in a small cylindrical beak, 

 forming a kind of case formed of a strong and transparent membrane. 



'he Electric ray (Torpedo marmorata). 



The Thornback, Jt. clavata (Fig. 359), so called in consequence 

 of its armature, inhabits every European sea; sometimes it attains 

 the length of twelve feet, and, being excellent eating, is much sought 

 after by fishermen. It is frequently seen with the skate in European 

 markets. A ray of great curving spines occupies the back and ex- 

 tends to the end of the tail ; two similar spines are above, and two 

 below the point of the muzzle. Two others are placed before, and 

 three behind the eyes. Each side of the tail is furnished with a row 

 of shorter spines ; the whole surface, in short, bristles with larger or 

 smaller spines, justifying the name of Thornback ; for these are not 

 given by way of ornament, but defence. The colour of the upper 

 surface is generally brown, with whitish spots. The tail, which ex- 

 ceeds the body in length, presents towards the end two small dorsal 

 fins, and terminates in a caudal fin. 



