72 
Dr. Wallich, on the Polycystina. 
regarded as an example of universal coalescence ; and, as I 
have elsewhere shown, it appears to serve an essential office 
in the deposition of the mineral substances of which the 
shells of the testaceous Rhizopods are composed. For the 
distinction of this very important layer I propose the name 
chitonosarc.'^ 
In this family the sarcoblasts are sometimes very con- 
spicuous, and more likely to be seen than in the Foraminifera, 
in consequence of the invariably crystalline texture of the 
skeleton. They are correctly described by Miiller as occu- 
pying a position, for the most part, immediately within the 
siliceous framework. There are exceptions to the rule, how- 
ever, arising from peculiarities in the configuration of some 
of the genera. 
Order II. — Protodermata. 
Characters. — Definite nucleus present, but no contractile 
vesicle. Sarcode so far advanced in differentiation that the 
ectosarc constitutes a nearly hyaline stratum of much more 
tenacity than the endosarc, which still retains much of the 
general consistence of that of the Herpnemata. The trans- 
ition, however, from ectosarc to endosarc is gradual, j Here, 
as in the last-named family, true vacuolar cavities occur. 
The pseudopodia, when present , are scattered and attenuated, 
rarely coalescing; for the most part rigid, but still highly 
contractile ; and exhibiting, in their interior and on the sur- 
face, only such minute granules as find their way into the 
ectosarc. Pseudo-cyclosis manifest. Sarcoblasts conspicuous. 
In this Order, as its name implies, we discover for the first 
time the evolution of an approach to membranous structure. 
But this does not occur in the more highly differentiated 
conditions of the ectosarc, which has already been alluded 
to, but in the capsule Avhich invests the nucleus. This cap- 
sule was pointed out by Professor Huxley as being present in 
Thalassicolla, at the same time that he laid down the Rhizo- 
podous nature of that organism. f I may mention that in the 
same year that his researches were published, and again in 
1857, I became acquainted with the appearance and intimate 
structure of Thalassicolla, Collosph(jera, and Sphcerozoum. 
But I entirely failed in tracing their affinities. From speci- 
* " Ou tlie Process of Mineral Deposit in the Rhizopods and Sponges," 
by G. C. Wallicli, M.D., ' Annals and Magazine of Natural History, Janu- 
ary, 1804," p. 72 et fseq. Prom x*^'^'^» ^ tunic, and trap?, flesh. 
t "On the Genus Thalamcolla^'" by T. H. Huxley, F.K.S., Surgeon Royal 
Navy, 'Annals and Magazine of Natural History,' 1851, 2nd ser., vol, viii, 
p. 431 ^/ {iCq. 
