Dr. Wallich, on the Polycystina. 
75 
belonging to the other Orders ; more particularly as the de- 
scriptions of their nature published by Huxley and Miiller 
leaves little to be done in the way of structural investigation. 
Leaving, therefore, a few incidental facts to be mentioned 
hereafter, I shall proceed to give a brief account of a new 
family I have set apart for the reception of a small and, to 
some extent, aberrant series of forms, namely^ the Dictyo^ 
chides. 
This family takes its name from the well-known objects to 
which Ehrenberg gave the generic designation of Dictyocha. 
If we picture an Acanthodesmia in which the siliceous skele- 
ton, instead of consisting of a single solid basket-shaped piece, 
is made up of two such portions, distinct from each other, like 
the valves of a diatom ; and which is, in addition, tubular 
throughout, we shall have a good idea of the nature of the 
siliceous framework of the Dictyochid(B. Their binary nature 
seems to become a link between them and the spiculiferous 
varieties of the Thalassicollina, whilst their tubularity deter- 
mines their alliance, in preference to any other family of 
Rhizopods, to the true SroNoiDiE. Of the tubular nature 
of these forms every microscopist may readily satisfy himself, 
under a careful analysis of balsam-mounted specimens.^ 
Order III. — Proteina. 
Characters. — A definite nucleus, and with it a contractile 
vesicle ; sarcode very highly differentiated into endosarc and 
ectosarcj the former granular, more or less nearly colour- 
less, very viscid, and exhibiting but little contractility j the 
latter nearly hyaline, very highly contractile, but never as- 
suming a membranous consistency, except during the period 
of en cy station. t Vacuolar cavities numerous and constant, 
seen principally to occur in the endosarc. Sarcoblasts abun« 
dant and frequent, but, owing to their pale colour, less easily 
detected than those of the oceanic Rhizopods. 
As already stated in an early portion of these observations, 
I regard the constant presence of such organs as a nucleus 
* According to the * Micrograpliic Dictionary,' Kiitzing enumerates no 
less than twenty -nine species, the sole distinction between these being derived 
from the varying number of these spines ! 
f In my observations " On Amoeba," already referred to as having ap- 
peared in the * Annals of Natural History' for 1864, 1 have fully stated my 
views regarding the reciprocal convertibility/ of the endosarc and ectosarc of 
the Rhizopods. I now refer only to the apparent condition for the time 
being, and without prejudice to my theory, which will, I believe, be found 
correct. 
VOL. XIII. 
