as Infusoria flagellata. 201 
pumila, Lamx., but is so excessively minute, and withal so 
transparent, excepting the body preper, that under a magnify- 
ing-power of five hundred diameters it appears to the casual 
observer like a mere globular speck. It was discovered when 
searching after specimens of Codoneca costata with a power of 
_ __ eight hundred diameters. Although sometimes met with in 
___ groups of forty or fifty, it always appeared single. In its 
general aspect it may be compared to an oval flask which is 
supported by a slender stem (pd), and has a broad funnel in- 
serted in its mouth. Upon close inspection we find that the 
funnel (0) is a direct projection from the body (which hangs 
freely within the flask, c c'), and is in no way connected with 
the latter. 
The body proper has a dark fuscous colour, and consequently 
is quite conspicuous. It is mainly oval in shape, but is con- 
stricted anteriorly into a short thick neck (¢), which terminates 
in a truncate front. It hangs quite loosely within the calycle 
(c), and usually at a considerable distance from its parietes ; 
but at the mouth (figs. 31, 32,c!) of the latter the neck (7) 
presses so closely against it as to seem, without the most careful 
 serutiny, to form a continuation with it. Occasionally, how- 
ever, the neck narrows and retreats from the aperture of the 
____¢alycle to such a degree as to allow a clear and unmistakeable 
: view (fig. 32) of the relations of the former to the latter. 
E The collar (6), which has just now been likened to a funnel 
set in the mouth of the flask-shaped calyx, is most frequently 
__ seen in a very broadly expanded state (fig. 28, 6), in outline 
resembling a low, obtuse-angled, truncate cone inverted upon 
the front of the body. It arises from the, extreme circular — 
margin of the head (7), and, widening to about twice the equa- 
torial diameter of the calyx (c), terminates in a smooth edge 
at an altitude which is hardly equal to one-quarter of the width 
of its distal expanse. It is hyaline, and so extremely thin and 
filmy as to require the most careful manipulation of the light, 
even with so high a power as eight hundred diameters, in order 
_to define its boundaries clearly. In its plasticity it is even 
more marvellous than that of Codosiga; at least it exhibits it 
over a far wider lateral range than the latter, and with equal 
rapidity in its changes. In a few seconds it narrows from its 
greatest expanse to the proportions of an obverted acute-angled 
cone (fig. 29,5), and at the same time assumes an altitude 
which is equal to the length of the body; and then, within an 
equally short period, it contracts into the form of a cylinder 
(fig. 30, b) whose height more than equals that of the calyx. 
These changes are carried on with the same peculiar vibrations 
as were noted in regard to Codosiga, reminding one of the 
