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. 
Fig. 360,—The Electric ray (Torpedo marmorata). 
The Thormback, &. 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. 
