248 H. P. KJERSKOG AGERSBORG. 



of the stomach of the star could not reach the vital parts of the 

 clam exposed by the relaxation of the adductor muscles. The 

 reason for the failure to kill the clam was due to the fact that the 

 syphon of the clam, as stated before, was extended into the mouth 

 of the star. The star seemed to have no effect on the clam, except 

 that the syphon was partly digested around the edges of its 

 apertures. Otherwise the clam seemed to have enjoyed the 

 gastric juices of the star; it was still alive and behaved like un- 

 molested clams of the same kind, when it was freed from its 

 pursuer. Small clams are more easily preyed upon. Ordinary 

 cockles are as a rule engulfed. In opening cockles or smaller 

 clams, Pycnopodia holds its prey until it has a chance to force 

 some of its everted stomach into the shell-fish, and having suc- 

 ceeded partly in this respect, it digests its prey piecemeal. In 

 other instances, members of the family Natidse (e. g., Nassa 

 mendicd) were found in the stomach of this starfish, together 

 with egg-bodies of Natidae. As a matter of fact, Pycnopodia feeds 

 especially on gasteropods, engulfing the smaller ones, as in the 

 case of the last referred to. Polynices, though a monster of a 

 slug, is a very easy prey, indeed, to Pycnopodia. In fact few, 

 of this slug are found on grounds common to Pycnopodia. 

 From experiment it was found that Polynices is very sensitive 

 to the surface of this star. When keeping several Polynices 

 in the aquarium with one Pycnopodia, it was found that the latter 

 devoured three large (foot, about 8 inches long, 5 inches wide, 

 and 4 inches deep) specimens in three days, leaving the shells 

 on the outside. The method of feeding on these slugs is simply 

 by suffocation. The slug seems to be incapable of living very 

 long within its shell, and unless it is allowed to take in fresh water, 

 when relaxing, it soon has to come out as a mere powerless, 

 defenseless matter of flesh. When, therefore, Pycnopodia has 

 Polynices in its control, the latter must very shortly give in to 

 the former. In still other instances, remnants of crabs were 

 found in the stomach of this star also. In this connection, 

 experiments on feeding it with crabs were actually performed. 

 Having stabbed a crab (Magister prodtictus}, it was thrown into 

 the water so that it would fall down beside or on the top of the 

 star. In one such instance, the latter seized the crab-fragments 



