21 



THE DOGFISH 



Various species of the small sharks known as dogfish are found 

 in British waters. One of the commonest in southern seas is 

 the lesser spotted dogfish or rough hound, Scyllium canicula 

 [=Scyliorhinus caniculus), but in the north this is replaced by 

 the larger spiny or piked dogfish, Acanthias vulgaris {=Squalus 

 acanthias). The following description applies primarily to the 

 former, but the chief differences of Acanthias are noted. Like 

 other dogfish, they justify their name by travelling in packs 

 and hunting by smell. They live usually near the sea bottom, 

 and feed largely upon crabs, hermit crabs, and other crustaceans, 

 though they also often devour shell-fish, or small fishes, and will 

 indeed take most kinds of animal food, dead or alive. They are 

 very voracious and are a nuisance to fishermen by taking the 

 bait meant for their betters. The flesh, though coarse, is used for 

 food. 



EXTERNAL FEATURES 



The length of a well-grown rough hound is about two feet. 

 Its slender body (Fig. 235), well shaped for passage through the 

 water, tapers from before backwards, and, though it shows no 

 sudd@n differences in size, there may be recognised in it a head. 



Fig. 235. — The Rough Hound. 



Note mouth, eye, spiracle, lateral line, gill clefts, pectoral and pelvic fins, dorsal fins, caudal fin, ventral 



fin between caudal and pelvic fins. 



c.f., Upper lobe of caudal fin ; c.f'., lower lobe of the same ; />/./., right pelvic fin. 



a trunk, and a tail, the hinder limit of the first being marked 



roughly by the hindmost gill slit (see below), and that of the trunk 



by the vent. The head is flat, and has a blunt-pointed snout, a 



wide, crescentic mouth on the lower side, a pair of round nostrils 



in front of the mouth and connected with it by oronasal grooves, 



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