LIST OF WOODCUTS. 



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

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



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



,, 3. ,, ,, VeNTKAL views of MALE and FEMALE 21 



,, 4. ,, ,, The gills 26 



,,5. ,, ,, Dissection fhom the dorsal side 



(male) 28 



,, 6. ,, ,, Longitudinal vertical section of 



THE alimentary CANAL . . 29 



,, 7. ,, ,, A GASTROLITH OR " CKAB's EYE " . 30 



,, 8. ,, ,, Attachment of young to swim- 



meret of mother . . . 41 

 ,, 9. ,, ,, Structure of the stomach . . 53 

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

 mach 56 



,, 11. ,, ,, KOOF 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 (jills . . . 76 



,, 18. ,, ,, The green gland . . . . 83 



