of England and India. 31 
I have described in Ameba princeps. In a figure of A. vulgaris 
which was active, there are twenty-one of these cells repre- 
sented ; and in another of the facetted variety (4. angulosa, Khr.), 
which was passive, these cells are all gathered up into the body 
of the animal, which has thus assumed a compressed circular 
form corresponding with that of the interior of the test, and in 
this state much resembles the condition of A. princeps when the 
body, filled with reproductive cells, has become almost effete and 
barely forms more than a protective covering to them. (Annals, 
ser. 8. vol. xu. pl. 3. fig.4). Huglypha alveolata is also represented 
in a similar state (Annals, ser. 2. vol. xviii. pl. 5. fig. 26). Hence 
I think it possible that the authors above mentioned may have 
mistaken these cells for.nuclei; at the same time, the apparent 
areolation of the nucleus, which arises from the circular semi- 
opake nucleolus being much smaller than the more transparent 
nuclear cell, is at the same time as characteristic of the nucleus 
as it is distinctive of it from the “‘ reproductive cell,” which has 
no areolation. It is, however, possible, as I have inferred in A, 
princeps, that these cells may arise from a division of the nucleus; 
and this, if I am right in my conjecture, may have led to their 
having been called nuclei. 
The depressed, arched, elevated, and facetted forms of Arcella 
respectively, one would have concluded, @ priori, to have been 
all variations from one type form, if this had not been confirmed 
by Claparéde and Lachmann (p. 446) through actual observation; 
and that type form one would further conclude to be A. vulgaris, 
if there were not room for doubt still left respecting the probable 
passage of the new test produced by the varzety returning to the 
original form,—that is, if the sagacious observers just mentioned 
had not only established that all the varieties which they have 
mentioned may come from A. vulgaris, but also that these varie- 
ties never returned to it. Beyond this I have nothing to add to 
their excellent article on the subject, saving that, if the green 
colour of A. viridis, Perty, should depend upon the presence of 
chlorophyll-cells, then I think this should be considered a dis- 
tinct species. 
wn figures are chiefly intended to bring the principal varieties 
together, for the purpose of showing their resemblance to each 
other, the identity in form of their pseudopodia with those of 
Diffiugia, and their size relative to the other Rhizopoda which 
are illustrated with them. They all are as common in the island 
of Bombay as here on the south coast of Devon. 
Arcella patens, Clap. et Lachm. (p. 446, pl. 22. fig. 7). 
This species (very like Ehrenberg’s Pywidicula operculata, 
tab. x. fig. 1, and placed by this illustrious microscopist among 
