LIST OF WOODCUTS. 



Frontispiece. The Common Crayfish, Astacus Jluviatilis, (male) 

 Fig. 1. Astacus fluviatilis. Side view of the male. 



Dorsal views of male and female 

 Ventral views of male and female 



The gills 



Dissection from the dorsal side 



(male) .... 

 Longitudinal vertical section of 

 the alimentary canal 



A GASTROLITH OR " CRAB'S EYE " 



Attachment of toung to swim 



MERET OF mother 



Structure of the stomach . 

 Longitudinal section of the sto 



MACH 



EooF of the stomach, from within 



Dissection from the side (male) 



Alimentary canal from above 



Blood corpuscles . 



Transverse section of thorax . 



The heart 



Structure of the gills 



The green gland . 



6 



18 

 21 

 26 



28 



29 

 30 



41 



56 



60 

 62 

 65 

 68 

 70 

 72 

 76 

 83 



