30 HISTORY OF CRUSTACEA. CHAP. V. 



CHAPTEK V. 



RESPIRATION IN LAND CRABS. 



AMONG the numerous facts in the natural history of 

 the Crustacea upon which a new and clear light is 

 thrown by Darwin's theory, besides the two forms of 

 the males in our Tanais and in Orchestia Darwinii, 

 there is one which appears to me of particular im- 

 portance, namely, the character of the branchial cavity 

 in the air-breathing Crabs, of which, unfortunately, I 

 have been unable to investigate some of the most 

 remarkable (Gecarcinus, Eanina). As this character, 

 namely, the existence of an entrance behind the 

 branchiae, has hitherto been noticed, even as a fact, 

 only in Ranina, I will go into it in some detail. I 

 have already mentioned that, as indeed is required by 

 Darwin's theory, this entrant orifice is produced in 

 different manners in the different families. 



In the Frog-crab (Eanina ) of the Indian Ocean, 

 which, according to Eumphius, loves to climb up on 

 the roofs of the houses, the ordinary anterior entrant 

 orifice is entirely wanting according to Milne-Edwards, 

 and the entrance of a canal opening into the hindmost 

 parts of the branchial cavity is situated beneath the 

 commencement of the abdomen. 



