ASTEROPHILA, A \K\V GENUS OF PARASITIC GAS- 

 TROPODS. 1 



JOSEPHINE RANDALL AND HAROLD HEATH. 



During the dredging operations of the U. S. F. C. Str. Alba- 

 tross in the vicinty of Japan (summer of 1906) four specimens of 

 a starfish, Pedicellaster sp., were taken that had been parasi- 

 tized by a new genus of gastropods. All were dredged in the 

 sea of Japan off the coast of Corea at depths ranging from 150 

 fms. (sta. 4,867) to 163 fms. (sta. 4,861). In one host three 

 parasites occurred, while only one was present in each of the 

 other three, but in any event they occupied the ccelom in 

 the arm, and were attached by connective tissue strands to the 

 body wall in the vicinity of the ambulacral ridge. As noted 

 more particularly hereafter, this species is not put in communi- 

 cation with the exterior, the mouth and reproductive openings 

 communicating with the body cavity of the host. During the 

 time that the brood pouch is crowded with embryos the 

 pseudollapium becomes accordingly considerably distended and 

 tense, resulting in the inflation and consequent thinning of 

 the body wall of the host along the dorsal side of the arm 

 (PI. II., Fig. 2). Under such circumstances it is possible that 

 the body wall of the starfish finally ruptures, causing a diminu- 

 tion of the pressure on the pseudopallium which therefore dis- 

 charges the embryos into the surrounding medium. After 

 this process the break in the body wall is probably repaired, 

 as there are evidences that one of the larger individuals has 

 recently discharged its brood though there are no signs of a 

 rent in the starfish arm. 



In every case the body resembles in form a kidney or thick-set 

 bean, and varies in size from i\\o to twenty millimeters, this last 

 extreme being due to some extent to the large number of embryos 

 and the fluid in which they float. The ovary and the embryos 

 themselves arc- light yellow in color due to the presence of yolk, 



1 Published by permission of Hon. G. M. Bowers, Commissioner <>t I-'Nu-ries. 



98 



