ASTACUS NIGEESCENS. 



245 



There are no cervical spines, and the middle part of 

 the cervical groove is angulated backwards instead of 

 being transverse. 



^— i 



B 



vv ! 



/-. 



Flo. 62. A k D, Astaois torvcntium ; B & E, .-1. nohiUs ; C & F, 

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

 endopodite of second appendage ( x 8). a, anterior, and b, posterior rolled 

 edge ; c, 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 



