144 INVERTEBRATE ANIMALS. 



of tlie thoracic legs. There is a well-developed abdomen, and there 

 are seven pairs of thoracic legs, directed partly forwards and partly 

 backwards. Good examples are the Sand-hoppers {Talitrus, fig. 

 92, A) and the " Fresh-water Shrimps " {Gammarus, fig. 92, B). 



The Sand-hoppers and Gammari swim on their side when in the 

 water, and the former leap with great activity on land. 



Fig. 92.— Anipliipnda. A, TalitTUs locusta, the " S.ind-hopper," enlarged. B, Ganivmrus 

 locusta, enlarged about four times. (After Spence Bate and Westwood.) 



Nearly related to the Amphipods are a number of little Crus- 

 taceans {Lii'iiindipodu), in which the abdomen is quite rudimentary. 

 Some of these {e.g., the Whale-lice) are parasitic in their habits, 

 and all inhabit the sea. 



OllDER MeROSTOMATA. 



Ill this order are only the living King-crabs {Limuhis), and some 

 large extinct forms nearly allied to them. They are all distinguished 

 by the fact that the appendages which are placed round the mouth 

 act by their bases as jaws, but have their extremities developed into 

 swimming-paddles, walking-feet, or nipping-claws. 



