ASTACUS NIGRESCENS. 



245 



There are no cervical spines, and the middle part of 

 the cervical groove is angulated backwards instead of 



being transverse. 



—e 



Fig. 62. A & D, AsiffU'Hs fnnrtitiuni ; B & E, A. noliiUs ; C & F, 

 A. nigrescens. A— C, Isb abdominal appendage of the male ; D — F, 

 endopodite of second appendage ( x 3). a, anterior, and h, posterior rolled 

 edge : <?, d, e, corresponding parts of the appendages in each species : 

 /, rolled plate of endopodite ; g, terminal division of endopodite. 



The abdominal pleura are narrow, equal-sided, and 

 acutely pointed in tlie males (fig. 61, F)— slight!}^ 

 broader, more obtuse, and with the anterior edges 

 12 



