H. B. Fantham 
399 
(2) Genus Siedleckia, Caullery and Mesnil. 
Trophozoites vermiform. Schizogony, by plasmotomy, only known. 
Sporogony unknown. 
One species. 
Parasite Habitat Host 
Siedleckia nematoides, Caull. and Mesn. Gut Scoloplos muelleri, 
Aricia latreilli, 
Aricia fcetida (Dobell) 
3. Family Selenidiidae, Brasil. 
Schizont intracellular, uninucleate during growth, becoming mul- 
tinucleate at the end of its development. Trophozoites (gametocytes) 
free, vermiform, motile, with longitudinal myonemes. 
One genus, Selenidium. 
(1) Genus Selenidium, Giard. 
This genus, as emended by Caullery and Mesnil in 1899, includes 
Polyrhabdina, Mingazzini (1891), Esarhabdina, Mingazzini (1891), and 
Platycystis, Leger (1892). 
The epimerite may be slender and conical, or large and globular 
(Caullery and Mesnil, 1899). The latter form is probably due to 
invagination (Brasil, 1907). Spores spherical, spined and tetrazoic. 
Parasites of Annelids (Polychaetes and Gephyrea). 
Many species, the majority of which are ill-defined, and need 
re-investigation, especially from the point of view of possible schizogonic 
stages. 
The following list, which has entailed much labour, is the first of 
its kind for the genus; it is hoped that it is complete. It has been 
considei’ed advisable to list the hosts in the first column, as so many of 
the species are unnamed. In view of our incomplete knowledge it 
appears inadvisable to supply names to such species of Selenidium. 
Host 
Habitat 
Parasite 
Remarks 
Aricia sp. 
Gut 
Selenidium sabellae, Lank., 1863 
Audouinia filigera 
J 5 
S. cirratuli, Lank., 1866 
Audouinia tentaculata 
5 J 
Selenidium sp., C. & M.*, 1899 
Cirratulus cirratus 
( = C. borealis) 
> > 
S. cirratuli , Lank., 1866 
Two species described by C. & 
M. (1899) 
Ctenodrilus serratus 
J 9 
Selenidium sp., C. & M., 1899 
* C. & M. = Caullery and Mesnil. 
Small size 
