GEN. CARCHARIAS. THE BLUE SHARK. 303 



be bluish-black. The length is about two feet. 



o 



The purse or bag which contains the young is of an 

 oblong shape, and has tendrils only at one end. 



Gen. CVI. CAUCHARIAS. This genus compre- 

 hends some of the sharks properly so called, fishes 

 of great size and voracity, well known to every 

 navigator in the Mediterranean and tropical seas, 

 and not strangers to our own coasts, although they 

 appear here on ] y at certain seasons, and in com- 

 paratively small numbers. Of the two which have 

 been noticed in the British seas, the least frequent 

 is 



(Sp 220) C.glaucus; the Blue Shark, which 

 migrates annually to our shores during the pilchard 

 and herring season. Its chief residence is the Medi- 

 terranean, where it may be regarded as common, 

 and is the species frequently seen following vessels. 

 It attains the length of six or seven feet. The whole 



o 



of the upper parts are of a slate-blue, and of the un- 

 der side nearly pure white. The teeth are triangular, 

 sharp-pointed and serrated on the edges, particularly 

 in the upper jaw, directed backwards, and diminish- 

 ing in size from the front to the hinder row. The 

 pectoral fins are very large, subfalcifonn, and ter- 

 minating in an acute angle, the dorsal and ventral 

 ridge indented at the setting-on of the tail. The 

 latter is divided into two lobes, the upper of which 

 is much the longest and falciform ; the under one 

 nearly triangular. Mr. Couch says that the Blue 

 Shark produces its young early in June. On the 

 coast of Cornwall, which is by far its most abun- 



