Dr. Wallich^ on the Polycystina, 
71 
Foraminiferaj and probably of all the Rhizopods. And where- 
as in the case of the marine and fresh-water genera I have 
been enabled to collect sufficient data to prove that these 
bodies^ although developed within the parent protoplasm^ be- 
come ultimately extruded therefrom ; and, in the testaceous 
forms, that the deposition of the shell-material dates, as a 
general rule, from this period ; the development of the "test/' 
whilst still within the parent sarcode (as originally stated by 
Ehrenberg and afterwards by Schultze), occurs in some 
examples amongst the Foraminifera, and brings the pheno- 
menon within the category of viviparous reproduction ; hence 
confirming my own discovery of this being a phase of the 
reproductive system of the Amoebans.'^ 
Passing on to the character of the sarcode substance of the 
Polycystina, I may remark that the appearances presented are, 
in every essential particular, identical with those observable 
in the Foraminifera ; the minor differences observable in 
the variation in number, size, and distribution of the pseu- 
dopodia being, as already stated, manifestly the consequence 
— or I should rather say the accompaniment—of equivalent 
differences in the foramination of the siliceous skeleton. 
In support of this view, it is but requisite to compare 
the pseudopodia of such Polycystina as Podocyrtis (Ehr.) or 
Encyrtidium (Ehr.) (in which they are comparatively few, 
much attenuated and scattered), with those of the spongy, 
and more particularly the discoidal, Haliommata (in which 
their number is as incalculable as the meshes of the minute 
siliceous network from whence they issue, and they consti- 
tute a dense, velvety covering which completely obscures 
the skeleton), to perceive at a glance that a much wider gap 
exists between the pseudopodia of these genera than is 
traceable between those of the two first-named Polycystine 
genera and those of a Rotalian Fo7^aminifer. 
But it remains still to note another point of resemblance 
between the characters of the Foraminifera and Polycystina 
afforded by their sarcode ; namely, that in all the latter the 
entire surface of the siliceous skeleton is enveloped in a 
more or less delicate film of protoplasm, formed by the 
coalescence of the extruded bases of the pseudopodia — or, in 
other words, of the pseudopodian stolons ; whilst in some of 
the Foraminifera, as averred by Williamson originally, and 
afterwards by Carter, Schultze, and Carpenter, and con- 
firmed by my own observation, such an investing film of sar- 
code is also to be detected. This layer may, indeed, be 
* On '■^ Amceha villosa,^'' by G. Wallicli, M.D., 'Annals and Magazine of 
Natural History' for June, 1863, p. 441. 
