of England and India, 31 



I have described in Amceba 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 {A. angulosa,'Ehr.), 

 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 efiete and 

 barely forms more than a protective covering to them. (Annals, 

 ser. 3. vol. xii. pi. 3. fig. 4) . Euglypha aheolata is also represented 

 in a similar state (Annals, ser. 3. vol. xviii. pi. 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 oiArcella 

 respectively, one would have concluded, a priori, to have been 

 all variations from one type form, if this had not been confirmed 

 by Claparede 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 variety 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. 



My 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 

 Difflugia, 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, pi. 22. fig. 7). 

 This species (very like Ehrenberg^s Pyxidicula operculata, 

 tab. X. fig. 1, and placed by this illustrious microscopist among 



