PARASITES OF SIMULIUM LARVAE 79 
myxosporidia respectively during the period of growth. This 
character disappears when sporulation begins, for in both fam- 
ilies the sporonts are surrounded with a fine membrane, and 
the myxosporidium therefore at this stage is multicellular in both 
families. As before stated, all the material I have examined 
was in rather an advanced stage of sporulation, so that this char- 
acter was poorly defined. As the earlier stages were not described 
by Léger (’97) or by Lutz and Splendore (’04), I conclude that 
their material was in about the same stage of maturation as 
that which I examined. In Glugea fibrata, however, I saw 
(pl. 3, figs. 4 and 5) what appeared to me to be free nuclei in 
the protoplasmic mass between the already formed sporonts. 
Some of these seemed to be still undergoing division. In G. 
bracteata also, sporonts appeared to be budded off from a mul- 
tinucleate mass of protoplasm (pl. 2, fig. 4). If my interpreta- 
tion be correct, both of these species certainly, and probably 
the other three also, belong to the family Glugeidae, and must 
therefore, as before stated, be provisionally placed in the genus 
Glugea. If this is not the case and the myxosporidium is multi- 
cellular during its entire development, these species will have to 
be placed in the Pleistophoridae, and, since Lutz and Splendore 
(08) show that octo- and polysporic development is not of generic 
value, all can be included in a modified conception of the genus 
Pleistophora Gurley, though that author limited the genus to 
polysporic, i.e., more than octosporic, species. 
THE EARLY STAGES OF INFECTION 
As stated in the detailed account of the various species given 
above, the early stages of infection and development were not 
found, and if, as I infer, they are present only in the youngest 
Simulium larvae, it is unlikely that these incipient stages will 
be readily discovered. From analogy and from observations upon 
the later stages it is, however, possible to trace the probable 
means of infection and subsequent development. 
As in all other Myxosoporidia, it may be assumed that infection 
is effected by way of the alimentary tract, and it is almost safe 
to say that this infection can take place only in the mesenteron, 
