H. B. Fantiiam 
405 
we have those with extracellular schizogony, i.e. ectoschizous forms, 
and those with intracellular schizogony ( e.g. Selenidiidae and Merogre- 
gcirinidae ) which are endoschizous. I would, then, divide the Schizo- 
gregarinae into two new sections, viz. the Homo'ica and Heteroica. The 
Homo'ica are divisible into two sub-sections, viz. the Ectoschiza and 
the Endoschiza. Including Merogregarina (Porter) this new classifica¬ 
tion is given in the accompanying table (p. 401). 
IX. Affinities. 
The position of the Schizogregarines in the general scheme of 
classification of the Sporozoa is clearly within the order Gregarinida, 
and the sub-class Telosporidia (Schaudinn). Further, the Schizogre¬ 
garines belong to the interesting assemblage of animals known as 
annectant forms. They link the Gregarines with the Coccidia, for in 
their trophic and sporogonic phases the Schizogregarinae resemble the 
Eugregarinae, while in the presence of an asexual multiplicative stage 
in their life-cycle they resemble the Coccidia. 
Before concluding, the interesting and unique form Schaudinnellci 
henleae (Nusbaum) may be mentioned for the light it sheds on the 
possible evolution of the Telosporidia. Schaudinnella possesses distinctly 
gregariniform, trophic phases, separate gametocytes without association 
or encystment stages, and well differentiated gametes, resembling in 
form those of Coccidia. The zygotes form sporozoites directly without 
the intervening formation of sporocysts. 
A gregariniform trophozoite has two courses open to it, either to 
become a schizont and by schizogony or multiple fission produce a crop 
of merozoites, or to become a gametocyte and pass through a process of 
gametogony, giving rise to gametes. In the Gregarines two gametocytes 
associate and form a common cyst. Then each gametocyte divides to 
form many gametes which conjugate in pairs, producing many zygotes 
or sporoblasts, the whole sexual process having taken place inside a 
gametocyst. On the other hand, in the Coccidia many gametes are 
formed from the male (micro-) gametocyte, but only one gamete from 
the female (macro-) gametocyte, and fertilisation occurs between free 
gametes which encyst after the zygosis. In Schaudinnella many micro¬ 
gametes are formed from each microgametocyte, but only a few (some 
8 to 10) macrogametes from each macrogametocyte, and conjugation 
occurs between the free gametes. In the occurrence of conjugation 
between anisogamous, free gametes Schaudinnella more nearly resembles 
