144 ANIMAL PARASITES AND MESSMATES. 



in the intestines, still keeping up a communication with 

 the exterior. A very common species of this class is called 

 Bopyrus. We often see beautiful prawns, which are 

 usually remarkable for their fine rose colour, exposed for 

 sale in shop windows. If we examine them at certain 

 seasons, especially in France, we perceive that the cara- 

 pace at the side is raised ; and if we take it off with some 

 precaution, we discover underneath an irregular flattened 

 body, which fishermen take for a young sole on account 

 of its shape. This is the female bopyrus. The many 

 appendages of the thorax, the division into rings, the 

 symmetry of the body, all have disappeared, and the 

 claws, the traces of which are scarcely seen, are no longer 

 similar on the right and left sides. The male remains 

 small and independent, and preserves the livery of the 

 order to which he belongs. On the coast of Labrador, a 

 bopyrus behaves in the same manner towards a Mysis. 

 We have found under the carapace of a pagurus a female 

 bopyrus full of eggs, so much flattened that it might 

 have been taken for a leaf accidentally introduced into 

 this cavity. 



Fritz Miiller has divided the Bopyridse in the follow- 

 ing manner : — 



1. Those which fix themselves on the appendages 

 or in the branchial cavity of decapods; these are the 

 Bopyri, lones, Phryxi, Gyges, Athelgi, &c. 



2. Those which live in the thoracic cavity of some 

 Brachyuri, as the Entoniscus, 



3. Those which live in the cirrhipeds, like the 

 Cryptoniscus, as well as the Liriopes. 



4. Those which live on copepods as true parasites, 

 as the Microniscus {M. Fuscus), 



