290 ZOOLOGY. 



the sharp hook-like legs around the margin of the body. The 

 head has no eyes nor appendages. The male (Fig. 257, 0, D) 

 is but slightly modified, is very minute, and is lodged partly 

 out of sight under the ventral plates of the female, whose 

 body is about five millimetres (a fifth of an inch) in length* 



Fig. SS&.Arcturus ciffi/d, w.tu its young clinging to its antennje. After Wyvillfr 

 Thompson. 



Various species of Porcellio (sow-bugs) live under stones 

 on land ; and allied to Asellus, the water sow-bug, is the 

 marine Limnoria lignoruni White, which is very injurious 

 to the piles of bridges, wharves, and any submerged wood. 

 The highest Isopods are Idotcea, of which /. irroratus Say 

 (Fig. 250) is our most abundant species, being common in 

 eel-grass, etc.. between and just below tide-marks ; and Arc- 

 turns (Fig. 258, A. Baffini Sabine), from the Arctic seas. 



