On the Respiration q/'Carcinus mfenas, Leach. 17 



Plate VII. 



Fig.l. Lernceotiema 2)olynemi. 5 > enlarged. 



1 a. Cephalothorax in young specimen, showing antennpe &c. 



1 b. Second peraeopod. 1 c. Fourth pera3opod. 1 d. Pos- 

 terior autenuse. 

 Fiff. 2. Peroden)ia hranchiuta, J , sp. n., enlarged. 



2 a. Tentacular processes, much enlarged. 



Fig. 3. Lernanthropus trifoUutus, $, sp. n., from underneath. 



3«. Seen from the side. 3 6. Under view of head from beneath, 

 3 c. Seen from the back. 3 rf. Anterior antennae, much 

 magnified. 



N.B. — Fourth peraeopod on right side of i?. triceros in Plate I. fig. 1 a 

 is drawn much too large. 



IT. — On the Resjnration o/Carcinus masnas, Leach^. 

 By Georges BoHNf- 



The common shore-crab {Carcinus mcenas), which is so 

 abundant on our coasts, especially on the shores of Normandy, 

 where it is called the furious crab (*' Crahes enrages "), and 

 where I have just been observing it daily for more than a 

 month, exists, as all are aware, under very varied conditions. 

 Some individuals bury themselves more or less in the mud ; 

 at low tide they are to be found hidden under stones or sunk 

 in the sand ; on the beach they run with rapidity, living as 

 much in the air as in the water ; in laboratories they are 

 kept alive for very long periods in crystallizing-paus : I have 

 seen some which have lasted more than a month in water 

 which was not changed, surrounded by dead animals and 

 rotten seaweeds. 



While investigating the influence of the habitat upon the 

 respiration of this crab, I have been led to observe a curious 

 phenomenon, which, so far as I am aware, has not hitherto 

 been described by anyone. I refer to the faculty of re- 

 versing for a longer or shorter period the direction of the 

 circulation of the water in tlie branchial chamber. 



Since the memorable observations of Audouin and Milne- 

 Edwards upon Maia and the "great " crabs of our shores every- 

 one has always followed these authors in stating that the 

 water enters by a particular point situated in front of the 

 anterior legs, and traverses the branchial chamber from 



* A study carried out at the marine laboratory of the Museum at 

 Saint-Yaast-la-Ilougue. 



t From the ' Comptes Eendus,' t. cxxv. no. 11 (September 13, 1897), 

 pp. 441-444. 



Ann. & Mag. N. Hist. Ser. 7. Vol. i. 2 



