CHAPTER XXIII. 



Crustacea {Crabs and Shrimps), 



* Continued, 



Perhaps the most singular of all animal existences, and 

 certainly the most remarkable of the Class to which they 

 belong, are those Crustaceans which constitute the Order 

 Epizoa, so called from their parasitical habits. The grand 

 principle of economy is so perfectly carried out in Crea- 

 tion, that not only is every spot of inorganic nature turned 

 to account in providing for some existences proper to it, 

 but even the bodies of living animals are made to afford a 

 dwelling-place and a feeding-ground for multitudes of 

 other creatures. The intestines, the layers of muscle, the 

 coats of the eye, the sinuses of the skull, afford, as we 

 have already seen,* in different animals, a home for cer- 

 tain creatures of strange conformation, which are found 

 under no other conditions, and are thence called Intes- 

 tinal Worms, or more correctly Entozoa, i. e., animals 

 which live within other animals. The gills of fishes, the 

 breathing pouches, the interior of the mouth, and various 

 parts of the surface of the body, become, on the other 



* See Chapter XIII., swjpra. 



