A bed of mussels barely three feet below the 

 surface was alive with crabs which I had had under 

 surveillance for the past hour or more. Although 

 their actions had not been devoid of interest, noth- 

 ing really novel occurred. In conformity with the 

 usual feeding habits of this species of spider-crab 

 (Libnia emarginata) , they had sought the mussels 

 after sunset, where they plucked off hydroids and 

 other zoophytes attached to the shells of the mol- 

 lusks. Occasionally this diet was varied by break- 

 ing open the mussels themselves; which they were 

 easily enabled to do with their powerful claws. 



Males and females in about equal numbers had 

 been thus employed; the former were easily iden- 

 tified from the latter by their claws and larger 

 size generally. All were sluggish in their move- 

 ments, their actions at times being grotesquely 

 deliberate. Their bodies, broad and round behind, 

 tapering to a point in front, were covered with 

 prickles and stubby hairs, to which often were ad- 

 hering particles of seaweed or debris; in some 

 instances barnacles and hydroids were seen at- 

 tached. Withal, their frowsy bodies, comparatively 

 small in proportion to their long slender legs, 

 would alone suffice to have given them their com- 



[211] 



