ELLOBIOPSIDAE 293 



show any important changes. In the following figure (d) the organ of fixation is divided into a larger 

 part which is largely external, and a smaller part in the lower region of the ovary of the host. In the 

 last figure {e) this smaller part is still visible. It forms a distinct prolongation of the organ of fixation, 

 penetrating the ovary of the host in a posterior direction. Moreover, the figures show sections of 

 trophomeres and gonomeres above the dorsal surface of the host. 



Fig. 4. Amallocystis fagei Boschma on Euphausia frigida H. J. Hansen from St. 751. Longitudinal sections of host; a, approxi- 

 mately in the median plane; b, slightly to one side. Letters as in Fig. i. In addition: /;/, heart of host; ov, ovary of host; 

 r, roots. X 107. 



It is interesting that the specimen on Th. gregaria is the only one in which the organ of fixation 

 possesses a prolongation of the kind described here. In the other specimens examined the organ of 

 fixation terminates in a blunt, somewhat broadened extremity. 



Externally the parasites of the various species of Euphausiids are very much alike. The larger 

 specimens may show a much larger number of trophomeres and gonomeres than the smaller specimens, 

 and in the latter the size of the trophomeres and gonomeres may be smaller than in the former, but 

 these differences do not point to a specific distinction. Moreover, internally the examined specimens 

 are almost entirely similar. As the organ of fixation of the specimen on Th. gregaria possesses a 

 distinct spur directed posteriorly, causing a slightly different aspect of this organ as compared to 



