34 



NATURAL HISTORY. 



from California. Both the latter are distinguished by having round black spots over the body and 

 fins. All the species are small. 



FAMILY VII. SPINACIDJE. 



This family includes ten genera. The genus Centrina is found in the Mediterranean, on the 

 coasts of Portugal. Acanthias, known from three species, like all the other members of the family, 

 wants the anal fin. The British representative is called 



THE PICKED DOG-FISH.* 



The Picked Dog-fish is the smallest and most abundant of British Sharks. It is most plentiful on 

 the west and south coasts, and Couch records that the sea is often covered with it for scores of miles, and 



TICKED DOG-FISH. 



that twenty thousand have been taken in a seine net at one time without visibly lessening their numbers. 

 It is a remarkably hardy fish, and never seems to suffer either from the severity of winter cold or 

 summer heat. The name is derived from the spines placed in front of each of its two dorsal fins. On 

 the coast of Kent and Sussex it is usually known as the Bone-dog ; in Orkney it is the Hoe ; in 

 Cornwall the male is known as the Skittle-dog. The spines are used as offensive weapons, and are 

 directed with marvellous accuracy against the object to be pierced. For nine or ten months in the 

 year the female produces young almost every day. The young are extruded in pairs, and develop 

 rapidly. Yarrell records that these Sharks have occasionally been found in a monstrous form, there 

 being two heads, with the separation continuing backward to behind the pectoral fins ; but there is no 

 evidence that such monsters attain to maturity. The young ones accompany their parents in pursuit 

 of prey, though their jaws are too feeble to capture or even attack the fishes on which their parents feed. 

 Frequently this fish bites jagged holes in the net, and cuts the hooks from the fishermen's lines. It has 



* Acanthias vulgar is. 



