318 ZOOLOGY. 



leech ; (Hirudo medicinalis ;j but differ from that 

 species in having a broad circular sucker at each ex- 

 tremity of their body. The surface of the body is 

 muricated or covered with tubercles, which are arranged 

 in transverse rows. The prevailing colour of the worm 

 is black ; some of the tubercles on the skin are white, 

 others yellow, black, or spotted ; the summit of the 

 narrower extremity of the body, or head, is marked 

 with two spots of a red-lead colour. 



These creatures adhered, by both their suckers, to 

 the tongue, palate, and gill-bones of the shark. When 

 removed they twirled actively in the hand, like fresh 

 water leeches, and travelled quickly over a dry surface 

 like the latter animals. Their bodies contained a large 

 quantity of red blood. 



The species must be regarded as a parasite; for I 

 am not aware that it has been seen in any other situa- 

 tion than adhering to cartilaginous fishes, as the shark 

 or ray ; from infesting which last it has obtained the 

 name of " Skate-sucker." 



