SEP 17 1896 [ 223 ] 



Contributions to Marine Bionomics. 



By 



Walter Garstang, M.A., 

 Fellow and Lectm-er of Lincoln College, Oxford. 



I. The Habits and Respiratory Mechanism of Corystes 



cassivelaunus. 



Corystes cassivelaunus is a crab of unusually narrow and elongated 

 form, which has received the popular name of " masked crab " from the 

 grotesque resemblance which its sculptured carapace bears to a human 

 face. It is common round all the coasts of the British Isles, and, 

 although normally an inhabitant of the deeper water, is occasionally 

 found at home in sandy pools on the sea shore, and is frequently cast 

 up in hundreds on sandy shores after heavy gales. 



I. Systematic Position. 



The systematic position of the Corystoidea has long been a disputed 

 point among carcinologists. Henri M. Edwards (1834) placed the 

 Corystoid crabs near the Dorippidai among the Oxystomata, and re- 

 garded them as connecting links between the Cancroidea {vid the 

 CalappidiTc) on the one hand, and the Anomoura on the other. 



De Haan (1849) removed the family from the group Oxystomata 

 altogether, and placed it with the Cyclometopa and Catometopa of 

 M. Edwards, in a separate sub-division of the Brachyura, the Brachy- 

 gnatha. 



Dana (1852) made of the Corystoidea an independent and primary 

 tribe of the Brachyura, distinct from the Cancroidea and Leucosoidea 

 alike. 



Alphonse Milne-Edwards (1860) reverted to the older view, and 

 placed the Corystida^ near the Calappoid Oxystomata. Heller also 

 (18G3) placed the Corystida^ among the Oxystomata. 



Finally, Claus (1880) definitely placed the Corystida? in the Cyclo- 

 metopa. In this he has been followed by Miers (188G) and Stebbing 

 (1893). 



NEW SERIES. — VOL. IV. NO. 3. R 



