408 
The Schizogregarines 
gametes formed from each gametocyte. There is good morphological 
evidence in support of this explanation (see p. 382, and Fig. 4, D). 
7. Figures of the interesting form Schizocystis gregarinoides (Leger, 
1900) are not yet published, but a paper dealing with this organism is 
promised by Prof. Leger at an early date. 
8. Aggregata differs from other Schizogregarines in that its 
schizogony takes place in one host (crab), while its sporogony occurs in 
another (Cephalopod mollusc). In this respect Aggregata resembles 
the Iiaemosporidia. The schizogonic phases in Crabs were formerly 
regarded as belonging to a gymnosporous Gregarin e, Aggregata Frenzel, 
while the sporogonic phases were considered to belong to a Coccidian, 
Eucoccidium (Benedenia) in cuttlefishes and Octopus. Regarding this, 
Ldger and Duboscq (1908, p. 102) write “ ...Aggregata, avec un 
changement de cycle co'incidant avec un changement d’hote, c’est a 
dire qui soient a la fois digenetiques et heteroiques.” 
9. It is evident therefore that the Aggregatidae stand apart. On 
this account, I suggest a division of the Schizogregarinae into two 
sections, termed respectively, the Homo'ica (to include the first four 
families discussed in this paper, wherein schizogony and sporogony take 
place in the same host) and the Hetero'ica (for the Aggregatidae). 
10. Among the Homo'ica we have extracellular schizogony (ecto- 
schizous forms) in the Ophryocystidae and Schizocystidae, and intracellular 
schizogony (endoschizous forms) in the Selenidiidae and Merogregarini- 
dae. This difference is not merely superficial, it requires to be 
emphasised, and for this reason I would divide the section Homo'ica 
into two sub-sections, termed respectively Ectoschiza and Endoschiza.- 
11. The classification of the Schizogregarines, which I would 
propose, is as follows: 
Schizogregarinae 
Homoica 
(nov. sect.) 
j Ophryocystidae 
Ectoschiza J f(?) Eleutheroschizon 
(nov. sub-sect.)) (Schizocystis 
‘Schizocystidae . 
J ((?) Siedleckia 
Endoschiza (Selenidiidae . Selenidium 
(nov. sub-sect.) (Merogregarinidae..Merogregarina 
.Heteroica. Aggregatidae . Aggregata 
(nov. sect.) 
12. Much further research is needed on the life-cycles of the 
Endoschiza, especially among the Selenidiidae, which occur so frequently 
in the Annelida. Sporogonic stages are at present unknown in 
Eleutheroschizon and Siedleckia. 
