ARTHROPOD \ 





some live in the gill chambers of higher Crustacea, and in such 



cases the dwarf males often live attached to the female. The 

 sexes are usually separate, but some parasites are hermaphro- 

 ditic, and in one hermaphroditic genus the animals are males 

 when young and females when they become older. The 

 land Isopoda are represented by such animals as the wood lice 

 or sow bugs (Fig. 154), which are very common under logs or 

 decaying wood. 



Order 2. Amphipoda 



The Amphipoda (Gr. «/-<•<£<', on both sides, and ttovs, foot) are 

 chiefly marine, but include some fresh-water species, like the 



2.. C y a m u s 



3. C a p r e I I a 



PlG. 156. Various Amphipoda. 3 a, male; b, female. (After Gerstaecker. and Rate and 

 Westwood, from Parker and Haswell's Text-book.) 



fresh-water shrimp, and some that may live on land, like the sand 

 hoppers or beach fleas ( Fig. i 55)- One genus is parasitic on the 

 skin of whales. In this order the body is compressed laterally 

 instead of dorsoventrally as in the Isopoda. There is often 

 more or less differentiation among the thoracic appendages. 

 The majority of them usually bear soft processes which function 



