Archer — On Freshtvater Rhizopoda. 
103 
a matter of course, must be, such an opening, is shown by the speci- 
men treated with acetic acid (J'ig. 12) ; for here the contents be- 
coming retracted, are partially extruded, and even the nucleus ex- 
pelled through the rather minute aperture at the apex, this frontal 
region assuming an appearance showing two transverse annular folds, 
giving a zig-zag lateral outline. It is this portion which, in both 
examples, in the living state is pushed inwards, giving the depressed 
and folded appearance then seen — the ^'boule" of Claparede and 
Lachmann. The anterior opening therein, indicated in Pig. 12, though 
seemingly so very small, must, however, be of considerable power of 
expansion to allow the entrance of so comparatively large an object 
as that shown within the specimen represented by Fig. 11, which pre- 
sents an example of Cosmarium cucurhita incepted as food. 
All this, then, seems to evidence that there must be attributed to 
these beings more than a shin — a distinct and separable test ; and this 
would bring the forms very close to Euglypha and Trinema in a generic 
point of view ; and, in fact, the widest distinction is the facetted test 
of the forms appertaining to those genera, and the absolutely smooth one 
here ; moreover, the behaviour of the pseudopodia is not alike in those. 
In a specific point of view, be these two, here drawn attention to, really 
mutually distinct or not, which I leave an open question, I need not 
urge that neither could for one moment, either in form or habit, be 
mistaken for any described Euglypha, or for Trinema. But, besides 
the smooth test, our forms are distinguished from those genera by the 
flexible infolded frontal region of the test, so unlike the rigid neck- 
like aperture of theirs, as the case may be, either prolonged exter- 
nally or introverted. 
In thus bringing forward these two forms to notice, I own they 
require a great deal more research ; perhaps, then, I may hereafter 
revive attention to them, should I obtain for any future observations 
the fitting opportunity. 
DESCRIPTION^ OF PLATES. 
Plate XII. 
Illustrating Me. William Aechek's Paper— On Freshwater Rhizopoda. 
Fig. 1. . . Amphizonellavestita (sp. nov.) showing the "corona" of pseudopodia, 
the outer coat, with its vertical, radial, and parallel markings, its 
clothing of very fine hair-like processes, the subjacent elliptic 
colourless bodies, a dense stratum of chlorophyll-granules beneath 
same, and the internal elliptic " nucleus ;" the latter, in this speci- 
men, posed at the side most remote from the pseudopodial region. 
In this example the chlorophyll-granules are very abundant ; no 
crude "food" making itself apparent. 
