ELLOBIOPSIDAE 295 



A. THE SPECIMEN ON HOPLOPHORUS GRIMALDII COUTlfiRE 

 The parasite (PI. XLI, fig. i) is attached to the ventral surface of the first abdominal segment of its 

 host. Its external part consists of a large number of trophomeres with gonomeres which are arranged 

 in separate tufts each provided with a stalk of considerable length. The tufts as a rule are composed of 

 ten to twenty trophomeres (Fig. 6) ; in PI. XLI, fig. 2, a side view of the whole mass of the external 

 part, about fifteen of the tufts are visible. Assuming that approximately one-fifth of the total mass of 

 tufts is visible in the figure the full amount of trophomeres in this specimen is estimated at 750-1500. 

 The whole mass of trophomeres and gonomeres as shown in the figures in PL XLI has a greater diameter 

 of 8 mm. and a height of 5 mm. The trophomeres have a conical shape, and they gradually broaden 

 towards their distal extremity, where they bear two or three (as a rule three) gonomeres. The latter 

 have a globular shape with the exception of the most distal gonomere, which as a rule is more or less 

 elongated. The thickness of the gonomeres varies from 165 to 225/^ ; the trophomeres are slightly thinner. 

 The arrangement of the trophomeres in tufts which are separately connected with long stalks to the 

 organ of fixation gives the parasite a superficial resemblance to a compound umbel. This peculiarity is 

 expressed in the trivial name wnbellatus. 



Fig. 6. Amallocystis umbellatus n.sp., type specimen. Tufts of stalks with trophomeres and gonomeres. x 15. 



One section of the parasite with its external mass of tufts of trophomeres and gonomeres is repre- 

 sented in Fig. 7. In the region of this section the external part as well as the internal part of the organ 

 of fixation are visible, the two parts being connected by a rather narrow neck. The internal part of the 

 organ of fixation is surrounded by a number of roots, some of which penetrate into the marginal parts 

 of the ventral nerve cord, whilst also in the tissues of the host directly under the cuticle there are also 

 numerous roots. Some of these roots are found at a considerable distance from the organ of fixation, 

 as, for instance, the one in the body musculature at the upper part of the left side of the figure. 



The figure, moreover, shows sections of seven or eight tufts of trophomeres and gonomeres. Of 

 some of these the stalks only are to be seen, of others stalks and trophomeres, and of others again 

 trophomeres and gonomeres. 



More details of the organ of fixation and of the root system are shown in Fig. 8. Here the stalks 

 with their trophomeres and gonomeres are not represented in the figures. The parts belonging to the 

 host are stippled, the organ of fixation with its rather strong cuticle is drawn with a double line, and the 

 roots are drawn with single rather thick lines. Fig. %a is the most anterior of the sections represented 

 here ; each following drawing is of a section from a more posterior region. The distances between 

 the sections figured are: a-b, looju; b-c, iiofi; c-d, go/i; d-e, 140//; e-f, izofi; f-g, 90/^; g-h, lOO/i; 

 h-i, 80//; /-;, 14.0/i. The section drawn in Fig. 7 is exactly between those of Fig. 8 g and h. 



In Fig. 8 a the anterior part (anterior in so far as it points to the anterior region of the host) of the 

 organ of fixation is found in the peripheral part of the ventral nerve cord of the host. It is indicated 



