MALACOSTRACA. 307 
congeners are probably related to certain ancient fossil forms from 
Paleozoic strata, e.g. Hymenocaris from the Cambrian. 
Fic, 160.—Nebalia.—Alter Sars. 
SH., Shell; 4.2, first antenne; A.2, second antenne; 7H., 8 thoracic 
limbs; 4é.4, 44.6, fourth and sixth abdominal limbs. 
Fic. 161.—Anaspedes.—After Calman. 
A.s, A.2, antenne; £x., rudimentary exopodite ; G., respiratory lamina 
PR.7, PR.S, seventh and eighth thoracic limbs or pereiopods; PL.s, 
2, 6, first, second, and sixth abdominal limbs or pleopods. 
