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of the spore. The shell is very thin and has the same thickness through- 
out, except two points of the truncated posterior end, where it presents 
a knot-like appearance. On its surface there are distinct striations, 
which are 8 in number and run almost parallel to the suture of the shell 
(Fig. 1). The most characteristic peculiarity of this species are its 
moderately long cilia, which attain 5,8 u in length and attach temselves 
in a single row along the posterior margin of the spore. Their point of 
attachment appears to meet with the end of the striation lines. Whe- 
ther they stand exactly so or not is not at present ascertainable, al- 
though I am inclined to believe it to be the fact. The polar capsules are 
symmetrical in form but not much closely apposed to each other. They 
are 3,8 u in length and 2 « in breadth. With 
a weak solution of glycerine, the capsular 
filament, which attains about 15 « in length, 
is easily extruded from the spore. The nucleus 
is obscure and there is no vacuole. This 
species differs from all known forms of Myxo- 
sporidia in as much as its general contour 
and the nature of cilia present very notable 
characteristics. At first sight, it presents some 
resemblance to Sphaerospora caudata, as both 
carry their cilia in a similar way; but the shape 
of the spore, the length of the cilia, the thick- 
Fig.1. Mitraspora cyprini. ness of the shell etc. do not allow them to 
Muchenlargedspore. a, Front Le classed as one and same species. It is not 
view; b, side view; c, ante- : 1 3 È 
rior view. quite exact even to classify this species as 
Sphaerospora, which has a spherical form as 
its prominent characteristic. Thus, considered from every point of view, 
this is a parasite altogether new and not yet into notice in this field of 
sporozoa. The generic name hitherto adopted by authors is based 
mostly on the nature of the spore, and following the same principle I 
have called it the Metraspora with the species name cyprini as it was 
first found in cyprinoid fish. 
2. Sphaerospora acuta n. sp. 
In the early summer, number of gold-fish are brought here for sale 
from Tokyo. I am informed that some of them, after lying on their side 
for some time finally die. This is generally believed to be the natural 
consequence of the abrupt change of their environment. I could not 
affirm the fact until such an accident happened to my fishes brought from 
the same locality. Then, all the internal organs were carefully exami- 
ned, but no obvious cause could be discovered. Finally, the gill was 
