796 
ZOOLOGICAL LITERATUllE. 
III. Definite nucleus ; contractile vesicle : Proteina. 
A. Monomorphous: Actinophryna. Actirnypluys. Gromia. Lagynis. 
Euylypha. Caclium ? Protocystis. Playi02)hrys ? 
D. Polymorphous: Amcebina. Amceha. JDiffiiiyia. Arcclhi. Pscu- 
clochlamys. 
The author then proceeds to characterize in detail each of 
these subdivisions^, but, unlike some of the writings of Dr. 
Ayallich, these details are too condensed to allow of further 
abridgement ; besides the paper is too valuable not to be con- 
sulted by those studying these forms. We therefore content 
ourselves by appending the divisions of the Polycystina into 
subfamilies. To understand this scheme it is necessary to bear 
in mind that in the embryonic stages of the skeleton of the 
Polycystina two distinct and very definite forms occur, which 
apparently never vary so far as to render their determination 
uncertain either in the earliest or any subsequent stage of 
growth of the organism. To the embryonic skeleton the name 
omphalostype is given; and to the earliest formed chamber, which 
is invariably formed around or upon the omphalostype, the name 
of the omphalic chamber is given. 
Family Polycystina. 
Animal presenting- the distinctive characters of the IIerpnemata gene- 
rally. Skeleton siliceous, of crystalline transparency, colourless, never tubular, 
continuous, foraminated, forming one or more compartments. 
I. Omphalostype 
symmetrical. 
Omphalic chamber 
spherical. 
II. Omphalostype 
asymmetrical. 
Omphalic chamber 
more or less pyra- 
midal and asym- 
metrical. 
Subfamilies. 
1 . SpHiERODiNA. Successive chambers arranged 
concentrically around the omphalic chamber, and 
developed upon and around the Acanthostypes 
which originate in the Omphalostype. 
Typical genus Ilaliomma (Ehr.). 
2. Dichodina. Successive chambers more or 
less compressed or discoidal, but interrupted at 
opposite poles. Typical genus Amphidiscits\W ii \.) . 
k Actinodina. Successive chambers com- 
pressed or discoidal and interrupted, forming two 
or more radiating lobes. 
Typical genus Astromma (Ehr.). 
1. Monodina. Successive chambers arranged 
• one in front of the other in linear series. 
Typical genus Pudocyrtis (Ehr.). 
Wallich (Ann. & Mag. Nat. Hist. 1864, xiii. pp. 215-245) 
considers that among the Difflugiclcs the animal does not vary, 
but it modifies the architecture of its habitation, and the mineral 
material of which that habitation is in a great measure con- 
structed, in obedience to local conditions and in the manner best 
fitted to meet its requirements.^^ In accordance with the views 
advanced in this important paper, the whole of the Testaceous 
Proteina may be accordingly arranged as follows ; — 
