NO. 7 A NEW COPEPOD HABITAT WILSON 5 



being many times the width of the body. The accompanying figures of 

 four different genera of sand-dwelHng copepods show their typical 

 Hnear form, which is admirably suited to their mode of life (figs, i 

 and 2). 



Fig. I. — a, dorsal view of a female Nitocra chelijer, a sand 

 dweller ; b, dorsal view of a male Arenosetella spmicauda, a sand 

 dweller. 



A third modification results in increased flexibility ; mere slender- 

 ness of body would contribute but little to freedom of motion unless 

 accompanied by flexibility. In the jointed body of the ordinary cope- 

 pod only one of the articulations is really movable, all the others being 

 more or less rigid and incapable of motion. In these copepods there 



