No. 403.] NOTES ON A SPECIES OF PELOMYXA. 549 
p. 313) of the backward flow of protoplasm from a pseudopo- 
dium : “ The viscid external layer cannot flow together rapidly 
enough to keep pace with this diminution, in consequence of 
which it is thrown into folds, etc." Returning to the expand- 
ing pseudopodium, I may say that Wallich’s remarks on Amæba 
villosa, quoted by Leidy (Joc. cit., p. 75) as applying to P. vil- 
losa, aptly describe the appearances to be had in P. carolinen- 
sts. After the local thickening of ectosarc, which precedes the 
formation of a pseudopodium, there is a sudden inrush of gran- 
ules. The very suddenness of this inrush inevitably suggests 
that something in front has burst or given way, rather than 
that something behind has egun to contract, and, as far as it 
goes, is an argument for Bütschli's theory (/oc. cit., p. 311), that 
the formation of a pseudopodium is primarily due to the bursting 
of superficial alveoli, whereby (through the action of the enchy- 
lema on the free surface of the protoplasm) the surface tension 
in that locality is diminished. 
Systematic. — In the assumption of complexly branched 
shapes (Figs. 6 and 7) P. carolinensis differs from the de- 
scribed conditions of the type species, P. palustris Greef, and 
of P. villosa Leidy, which are habitually more or less slug-like 
when in motion, and of massive shape when at rest. The 
peculiar posterior “ villi” characteristic of the latter form are 
absent in P. carolinensis, which, moreover, differs from both 
forms in the fact that it does not gorge itself with mud, and 
that it contains no * Stäbchen " or symbiotic bacteria, as they 
are believed to be by Gould (/oc. cit.) and some other observers. 
The Glanzkórper (albuminous globules) are present in Greef's 
species, and Leidy describes them in P. villosa. Blochmann 
(oc. cit.) and Frenzel (Joc. cit.), however, mention their absence 
in the forms which they identified as belonging to P. villosa. 
The minute crystals which I find so abundantly in P. caroli- 
nensis are apparently not present in P. palustris. Neither 
Greef nor Gould mentions them, nor were they found by 
Leidy in P. villosa. Possibly the granules which Blochmann 
finds in such quantity in some of his Pelomyxas correspond to 
my “crystals.” The Pelomyxas in which Blochmann finds the 
granules abundant have large and conspicuous Glanzkorper, 
