ASTACUS NIGEESCENS. 



245 



There are no_cervical_spines, and the middle part of 

 the cervical groove is angulated backwards instead of 

 being transverse. 



Fig. 62. A & D, Astaem torrentium ; B & E, A. noUUs ; C & F, 

 A. nigrescens. A — C, 1st abdominal appendage of the male ; D — F, 

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

 edge ; o, 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 the males (fig. 61, F) — slightly 

 broader, more obtuse, and with the anterior edges 



