PROTOZOA OR SIMPLEST ANIMALS. 
9 
(Imperforata, Fig. 4), or have, in addition to the main aperture, the 
wall of the shell perforated by numerous pores (Perforata, Fig. 5). 
Calcareous imperforate shells (see Family II.) have an opaque white 
porcellanous appearance, and perforate shells, in their early stages, 
a vitreous appearance (Families V. to X.). The shell may consist of 
one chamber (. Lagena , Family YU.)? c> r of many, arranged in linear, 
spiral, or concentric series, or on each side of a middle line. 
In GloUgerina , Rotalia , &c. (Family VIII. and IX.), all the 
chambers of the “ rotaliform ” spiral are visible from above, but 
Fig. 7. 
Shells of Globigerina, showing lower and upper surface. Magnified. 
only the last coil from below. In Nummulites (Family X. and 
Introductory series) the last coil of the spiral wholly encloses all the 
preceding coils. 
Although many of the specimens in the Case are very small, yet, 
with the aid of the diagrams, the shape can frequently be made out ; 
in some species the shells attain to relatively immense proportions, 
as Cydodypeus carpenterii (Family X.), from Borneo, with a thin 
discoid shell over two inches in diameter. 
The Foraminifera have played an important part in forming 
High WaH 
Case 
E. end of 
Gallery. 
