110 Helicosporidium parasiticum 
of several species of Crustacea, belonging to the genera Cypris, Daphnia and 
Gammarus. 
The descriptions and figures of this author are, however, very superficial 
and incomplete, and it is hardly possible to get a general idea of the structure 
of the parasites which he has described. 
Neither his descriptions nor his figures of some eight distinct species of 
this genus give the remotest indication as to the character which these species 
have in common. From his description one can only say that the few characters 
which are common to all his eight species are of no systematic value, namely 
(1) that these species live as parasites in the body cavity of Crustacea, (2) that 
they produce very numerous spores, (3) that their structure and life-cycle are 
equally obscure. 
From the systematic point of view the term Serumsporidium has no more 
value than the term ‘'blood parasites” applied to protozoal parasites of 
mammals. 
It is almost certain that his “ Serumsporidium IT (Miilleri), nov. sp.,” 
“ Serumsporidium gammari ’ and especially “ Serumsporidium cypridis IV, 
n. sp.” are the spores of a gregarine liberated from the ripe cysts, which, being 
fragile, have become ruptured inside the body of the host. 
From all his descriptions and figures those relating to his species “ Serum¬ 
sporidium ( Cytamoeba? Labbe) cypridis I, nov. sp.” (p. 12), are of especial 
interest to us, as three of the figures illustrating this species bear some 
resemblance to Helicosporidium. His figure 2, B. 7 (p. 12), for instance, recalls 
the morula of Helicosporidium composed of four cells, one of which is concealed 
behind the other three, while the Figs. 2, B. 8 and B. 9, resembles somewhat 
the spores of Helicosporidium which shows the three nuclei of the central 
cells only. It is, however, hardly possible to base upon these superficial 
resemblances anv relationship between Serumsporidium and Helicosporidium. 
4. Helicosporidium and Mycetozoa. 
Helicosporidium, has no affinities with the Mycetozoa, several species of 
which have been already found parasitic in insects. It differs from the 
Mycetozoa in the absence of the plasmodium and flagellate stages and by the 
complicated structures of the spores, which, on the contrary, are simple in 
Mvcetozoa. 
* • 
V. Conclusions. 
The foregoing evidence shows clearly that the genus Helicosporidium 
differs markedly from all the actually known Protists, and that it forms a new 
type which may be temporarily included in the group of the Sporozoa. It is 
possible that the discovery of other new forms of Protists, parasitic in insects, 
will throw more light upon the systematic position of Helicosporidium or will 
lead to the finding of a connecting link between this new genus and the already 
well-known forms. 
The genus Helicosporidium may be characterised as follows; 
