256 
W. M. Wheeler 
10. The Parasites of Myzostoma. 
The species of Myzostoma^ though themselves parasitic, are 
infested in turn with parasites. In Nansen’s fine paper ('85, pag. 63 
PI. 8 Fig. 25) there is a brief account of a tape-worm Cysticercus 
which he discovered in the alimentary tract oi M. graffi\ to this 
parasite he gives the name Taenia myzostoma. 1 have not happened 
on this or any other Taeniae, in looking over iny sections, but I 
have found two new parasites, an Amoeha and a species of Distoma^ 
both of which may be briefly described. 
Amoeha myzostomatis n. sp. 
Under this name I woiüd describe, at least provisionally, a 
peculiar amoeba-like form — possibly the yoiiug of some Gregarine 
— which occurred in great numbers in the body-cavity of a large 
M. glahrum^ the sections of which were stained with iron-haema- 
toxylin and Orange G. The body-cavity was distended with young 
and nearly full-grown ova. Among these — five of which I repro- 
duce in PI. 12 Figs. 52—55 — occurred the amoeboid organisms. 
In most cases the uniformly stainiug and rather shrunken body of 
the parasite was produced into a long fine point which had pene- 
trated the cytoplasm of an ovum. In a few instauces a single 
Amoeha had two points, each entering the body of an adjacent 
ovum (Fig. 54). The cytoplasm of the ova thus attacked contained 
large granules which took up the haematoxylin with avidity. These 
granules were larger and more numerous than those which occur 
in normal ova of about the same stage (cf. PI. 10 Fig. 23). A region 
of the cytoplasm immediately surrounding the point of the Amoeha 
was free from these granules, of the same orange stain as the parasite 
and exhibited a peculiar radiation, not unlike the radiation of an 
astrosphere at the pole of a karyokinetic spindle (Fig. 52 and 54). 
The point did not completely fill out the indentation which it had 
made in the cytoplasm of the ovum. This is seen in Fig. 55 where 
both puncture and point are cut transversely. This condition is very 
probably due to a shrinkage in the protoplasm of the Amoeha oc- 
casioned by a loss of water during preservation. 
Occasionally Amoebae were found which were not in the act of 
puncturing the ova. Two of these which appear as rounded masses 
of protoplasm are represented in Fig. 56 [am). Each contained, be- 
