292 DISCOVERY REPORTS 



(5) Specimen on E. frigida from St. 665 (Fig. T,b). In this specimen the organ of fixation does not 

 show a constriction between the external and the internal parts. The sieve plate is present on one side 

 of the parasite. As in the preceding specimen the organ of fixation is largely surrounded by chitinous 

 matter. 



(6) Specimens on E. vallentini from St. WS 770 (PI. XL). Here the Euphausiid is infested by two 

 specimens of the parasite of approximately the same size and shape. One (the right of the upper 

 figure of PL III) is embedded in the ovary of the host slightly before the other. The parasites show 

 a distinct neck-like constriction between their external and internal parts. The figure shows the sieve 

 plate of the hindmost of the two parasites, and the protoplasmatic excrescences protruding through 

 this plate. In the upper part of the figure sections of a number of trophomeres and gonomeres are 

 visible. 



Fig. 3. Amallocystis fagei Boschma on Euphausia frigida H. J. Hansen. Transverse sections of hosts, a, specimen from St. 766; 

 b, specimen from St. 665. Letters as in Fig. i. In addition: ", gonomere. x 70. 



A more enlarged photograph of part of a section next to the one of the upper figure is given in the 

 lower figure of PI. XL. It shows the lower part of the organ of fixation with the sieve plate and the 

 protoplasmatic excrescences protruding through this plate. The figure shows further that the cuticle 

 of the organ of fixation is rather thick, and that in some parts, especially in the right side of the figure, 

 it is strongly wrinkled. On the proximal parts of the protoplasmatic excrescences also a cuticle has 

 developed, though it is much thinner than that of the organ of fixation. 



(7) Specimen on E. frigida from St. 751 (Fig. 4). The host was sectioned longitudinally. One of the 

 sections (a) shows a median section of the parasite. Its organ of fixation does not present a pronounced 

 constriction between the internal and external parts. The external part broadens into the common 

 basal part of the trophomeres. The sieve plate is found in the lower part of the organ of fixation, 

 pointing to the posterior region of the host. Through this plate protoplasmatic excrescences are seen 

 to extend into the ovary of the host, where they divide into a well-developed root system. In this 

 specimen the root system is pronouncedly different from other spaces in the ovary, so that the exact 

 number of roots occurring in the sections could be drawn. At its sides the parasite is surrounded by 

 irregular masses of chitin. 



The other drawing (b) is after a section not far from the first one. It shows that the roots penetrate 

 for a rather long distance towards the posterior region of the ovary of the host. 



(8) Specimen on Thysanoessa gregaria from St. 871 (Fig. 5). Five sections are drawn, each section 

 being at a distance of 20/^ from the next. In the section of the most anterior part of the host {a) the 

 cuticle of the organ of fixation is represented ; on its inner wall it shows small excrescences which prove 

 that this part represents the sieve plate. The next figure {b) shows the organ of fixation, a protoplasmatic 

 excrescence, and some chitinous matter enveloping the organ of fixation. The next figure {c) does not 



