242 BOPYRID^E. 



In addition to Mr. Templeton's specimens, we have 

 received the male and female of this species from Pol- 

 perro, collected by Mr. Couch, as well as a coloured 

 drawing of a specimen which we also consider to belong 

 to this species from St. Andrews ; having been taken by 

 Mr. Mclntosh. It was first found by Rathke upon 

 Pagurus Bernhardus on the Norwegian shore. 



Athelgue fullode of M. Hesse, Ann. Sc. Nat., ser. 4, 

 vol. xv. p. 97, pi. 9, appears to us to belong to this 

 species. 



With reference to the question how the Bopyrus can 

 survive when the crab throws off its exuvium, Dr. Fritz 

 Miiller writes to us " When the crab casts its skin, 

 there can be no doubt but that the Bopyrus must go 

 along with it ; but as the crab, immediately after exuvia- 

 tion, is in an almost helpless and motionless condition, I 

 think that the Bopyrus may crawl again into the branchial 

 cavity. I shall send you a Porcellana, the integuments 

 of which are so soft that it must have moulted very 

 recently, and notwithstanding it has a very large Bopyrus 

 in its branchial cavity. Moreover, it seems to be im- 

 possible that the considerable deformation of the carapace 

 of the crab produced by the Bopyrus could disappear by 

 exuviation ; but I never found a deformed carapace with- 

 out the Bopyrus, although I have examined more than a 

 hundred Porcellanae bearing the parasite." " I may here 

 observe, in Bopyrus Porcellarue the right side is more 

 developed than the left when the parasite dwells in the 

 right branchial cavity, whereas the left side is the larger 

 when the Bopyrus dwells in the left branchial cavity. 

 The Bopyrus being fixed with its head directed backwards 

 naturally in the right branchial cavity, the right side of 

 the parasite can freely extend downwards, and therefore 

 becomes larger." 



