568 
DR. carpenter’s RESEARCHES ON THE FORAMIN IFERA. 
dividing cc' and dd' these interseptal canals seem to communicate by 
short lateral twigs with the cavities of the adjacent chambers, whilst at 
g, g, g become connected with vertical branches, which unite them 
with those of other planes: at hh, h' h' are seen the canals proper to the 
annular septa. 
Fig. 12. Thin section of Cycloclypeus, passing through its central plane, showing por- 
tions of four annuli, 1 1, 2 2, 3 3, 4 4, with the general relations and con- 
nexions of their chambers, the double septa by which they are separated, 
and (in parts) the interseptal system of canals: — 36 diam. 
PLATE XXX. 
Fig. 1. General view of a disk of Cycloclypeus, showing the aspect of its surface, and 
the appearances presented by horizontal and vertical sections: — 12 diam. 
Fig. 2. Surface-view of a full-grown specimen of Heterostegina, showing its tendency 
to assume the discoidal form by the opening-out of the spire: ah c, the thick- 
ened margin of the spire ; cda, its growing edge or mouth : — 10 diam. 
Fig. 3. Monstrous specimen of Cycloclypeus, having a vertical plate superimposed 
upon the horizontal disk : — 5 diam. 
Fig. 4. Ideal figure of a portion of a Cycloclypeus-6\s\i laid-open to show the details 
of its structure: a, a, a, upper stratum, consisting of superimposed tubular 
laminae ; h, h, h, portion of lower stratum ; c, c, c, cones of non-tubular 
substance, sometimes perforated by larger canals; d, d, d, their bases pro- 
jecting on the surface; e, e, plates of non-tubular substance, continuous 
with the septa between the chambers ; passages of communication 
between the chambers, through the inter-annular partitions, as seen in 
section ; g,g, the same as seen from the interior of the chambers ; h, h, inter- 
septal canals cut across ; i, a chamber on tlie walls of which the system of 
interseptal canals is represented as fully displayed ; h, k, passage of the 
principal canals along the line of junction between the roof of tlie chambers 
and the vertical septa: — 60 diam. 
PLATE XXXL 
Fig. 1. Section of a young specimen of Heterostegina, taken parallel to the surface, 
partly through the chambered plane and partly (owing to a slight inequality 
of the specimen) through the shelly investment of the chambers, the boun- 
daries of which, however, are still distinguishable, owing to the dilference 
of texture between the shell that covers the chambers and that which unites 
with the septa : a, first cell ; h, second cell ; c c, first subdivision ; d, second 
subdivision ; e,e, large passages connecting the chambers that abut on the 
pre-forrned whorl : — 60 diam. 
