LIST OF WOODCUTS. 



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



Fig. 1. Astacus fluviatilis. Side view of the male. . . 6 



2. ,, „ Dorsal views of male and female 18 



3. „ „ Ventral views of male and female 21 



i. „ „ The gills 26 



5. „ „ Dissection from the doesal side 



(male) . ... 28 

 ,, Longitudinal vertical section of 



the alimentary canal . . 29 



„ A gasteolith or "crab's eye" , 30 

 „ Attachment of toung to swim- 



meeet of mother . . . 41 



„ Structure of the stomach . . 53 



10. ,, ,, Longitudinal section of the sto- 

 mach 56 



11. ,, „ Eoof of the stomach, from within 60 



12. ,, ,, Dissection from the side (male) . 62 



13. „ ,, Alimentary canal from above . 65 



14. ,, „ Blood corpuscles .... 68 



15. „ „ Transverse section of thorax .. 70 



16. „ ,, The heart . 72 



17. „ „ Structure of the gills . . 76 



18. „ „ The green gland .... 83 



