10764 The American Naturalist. [December, 
diatoms, though belonging always to small species, occupy, each 
of them, a relatively large place on the shell, and give rise to a 
very general deformation of its otherwise regular contours (as 
‘indicated by the chitinoid substratum), Sometimes among the 
diatoms are to be found one or two quartzose grains. In the main 
the structure of the shell is the same as that of Diff. bacillifera 
Penard, but the form and size are different. Besides,—and this 
is the most important character of the species,—the plasma has 
normally and constantly a beautiful brick-red color, resembling 
that, for instance, of Vampirella lateritia Fresenius. It would have 
been interesting to investigate if in this species the pseudopodia 
present in their outstretched state the general colorization of the 
plasma. Unhappily all the animals were at the time of examina- 
tion retracted in their shell and in course of encystment; and in 
spite of observations extending over a space of more than two 
weeks, I have never noticed an extended pseudopod. Yet from 
analogy with what I have seen in Vampirella lateritia, and in an 
Heliozoon (Artodiscus saltus Penard), I am inclined to think that 
the pseudopodia, or at least their terminal parts, must be deprived 
of colored matter. It is perhaps not useless to add that the red 
color had certainly nothing to do with foreign matter, alge or 
digested products. The nucleus, generally invisible, was never- 
theless sometimes quite distinct; acetic acid brought it easily to 
view. It did not differ in any respect from ‘the nuclei of other 
Rhizopods. No contractile vesicle was present, owing very likely 
to the encysted state of the plasma. 
Ameba ———, sp. nov.?—This amceba was rather abundant, 
and very constant in its form and organization; yet I have 
not followed it long enough to describe it as a new species. It 
was very small (diam., 0.010 mm., without the pseudopodia), and 
consisted of a spherical, clear body, normally covered by a layer 
of greenish, but not shining, transparent globules, finely punctulate, 
about 0.002 mm. in size, and forming a continuous envelope. 
These globules were apparently of protoplasmic nature, and a 
product of secretion of the animal itself. They were mostly asso- 
ciated with a small number of shining, irregular particles of what 
appeared to be amorphous siliceous matter. Sometimes, how- 



