286 COMPARATIVE ZOOLOGY. 



Wood-louse, or Sow-bug (Oniscus\ so common in damp 

 places, the Slaters (Idotea), and the Sand-fleas (Gammarus), 

 seen by the sea-side. 



4. Decapods^ having ten legs, as the Shrimp (Cmngon\ 



Fie. 267 Swimming Crab (Platymychw). 



