741 



The large purple pycnogonid [Anoplodactylus lentus Wilson) so 

 abundant at Woods Hole is most commonly found associated with 

 colonies of Eudendrium ranioswn^ and it has always been the natural 

 inference that it obtained its food from this hydroid. It was difficult to 

 understand, however, how the pycnogonid could obtain the juices of the 

 hydroid by inserting its proboscis through the perisarc and so into the 

 gastral cavity of the latter, since the proboscis of the pycnogonid has 

 fully as great if not a greater diameter than the pycnogonid has fully 

 as great if not a greater diameter than the stems of the hydroid. But in 

 observing these pycnogonids at the United States Bureau of Fisheries 

 laboratory at Woods Hole during the past summer (1905) I found that 

 they probably do not suck the juices of the hydroids at all; on the other 

 hand they were observed eating off the hydranths. 



Specimens of Anoplodactylus were placed in a large dish or small 

 aquarium with a freshly collected colony of Eudendrium. Here, with 

 the aid of a reading glass, their actions could readily be observed. When 

 the pycnogonid came into contact with a hydroid head the latter was 

 seized firmly with the chelae and appeared to be forced slowly into the 

 mouth. The pycnogonid then pulled away until the hydranth broke 

 off, when it was gradually consumed, the chelifori aiding in the process 

 by helping to force the hydranth into the mouth. The hydranth was 

 sometimes broken up more or less by the chelae, and the pieces then 

 appeared to be sucked in. An animal eating steadily soon consumed a 

 considerable number of hydranths, and where these pycnogonids are 

 abundant, as they frequently are, they must be a serious enemy of the 

 hydroid colonies. 



While speaking of Anoplodactylus it may be worth while to mention 

 that during the past summer I had ample opportunity also to confirm 

 my observations made in 1900^ on the transfer of the eggs from the 

 female to the male, wliich I was able to watch this time in a number of 

 cases. The process was also observed independently by Mr. H. E. 

 Jordan, a student at the Marine Biological Laboratory, whose obser- 

 vations agree in all essentials with my own. About the only addition I 

 have to make is that it was noticed that the ovigera of the male were 

 sometimes attached to the egg-mass while the animal was still on the 

 dorsal side of the female, before he had worked around to the ventral 

 side as described in my former paper. 



5 Cole, Leon J., Notes on the habits of pycnogonids. Biol. Bull. Vol. 2. p. 195 

 —207. 1901. 



