252 Tue Microscope. 
appears to be much larger and stouter than Galea, judging by 
the figures of the latter in Kent’s Manual of the Infusoria, 
plate 59, Fig. 6, and this expression in the diagnosis: 
‘“* About three times as long as broad.” The zcodendrium of 
our form is articulate like that of Galea but is not ‘relatively 
short [and] thick ” as in that species; on the contrary, it is rel- 
atively slender and one of the tallest known. The cuticular 
surface is not smooth, but striate, and the vestibular entrance 
does not project snout-like. 
Concerning the significance of the two forms my observa- 
tions add nothing to what appears in the manuals relating to 
other genera. Noother species of Epistylis has been observed 
to possess such marked differences in the character of individu- 
als among the clusters. At first I inclined to the opinion that 
on this account it was generically distinct and Heteroepistylis 
occurred to me as a fitting name, but I remembered that 
ZLoothamnium was separated from Carchesium on similar 
grounds, but that its present validity rests upon an entirely dif- 
ferent character, viz: that of the muscular fibrilla of the pedicle 
rather than upon the polymorphism of the zooids; moreover, 
the relation of the two forms is an unsolved problem. It ap- 
pears to relate to the genetic reproduction of the species. 
A similar modification has been recorded as occurring in 
Zoothamnium alternans by W.8. Kent, Manual of the Infuso- 
ria, page 696. He remarks as follows: ‘It is anticipated by 
the author that these attenuated zooids represent male units 
destined to compass genetic union with the large subspherical 
and subsequently detatched animalcules of the normal colony 
stock. Phenomena substantiating this anticipation have yet to 
be recorded; even should this not be forthcoming Z. alternans 
will afford one of the most remarkable known instances of pol- 
ymorphism among Infusoria, in no other type being there three 
distinctly differentiated zooidal forms.” I have not discovered 
what was taken to be a third form or one to agree with the 
“large subspherical animalcules of Z. alternans;” on the other 
hand, those occur which I have called intermediate between 
the two described above. 
During September and October many groups were exam- 
ined and in no case of colonies of more than a few zooids were 
