GENUS CAEPENTEEIA: — EXTEENAL CHAEACTEES. 
565 
like that of certain Foraminifera, whilst the fleshy substance occupying its chambers is 
strengthened with spicules like those of Sponges. Hence he considered this organism 
in the light of a Sponge enveloped in a shelly case with a single terminal oscule. My 
opinion as to its character having been asked by Dr. Geay, I soon found reason to accord 
with him in his general idea of its affinities ; the structure of the shell being most 
characteristically foraminiferous, whilst the substance occupying its chambers is no less 
characteristically spongeous. In communicating this result, however, to Dr. Geay, I 
thought it right to suggest the possibility that this spongeous substance might be para- 
sitic ; the tendency of certain Sponges to find their way into even very minute fissures 
and passages ha\dng been observed by me in my researches on the structure of the Shells 
of Mollusks. Dr. Geay agreed with me in thinking this improbable, for reasons which 
will be presently stated ; and he communicated a general account of this new type (to 
which he did me the honour of giving my own name) to the Zoological Society* ; at 
the same time expressing the desire that I should include a fuller account of its forma- 
tion and structure in my communications on the Foraminifera to the Royal Society. 
With this desire I have now the satisfaction of complying. 
226. External Characters. — The ordinary external aspect of Carpenteria., as represented 
in Plate XXII. figs. I, 10 (taken from a group on the surface of Porites, of which the 
individuals are in close proximity to each other), at once suggests a resemblance to the 
Balaniform type ; the shell being conical, attached by its broad base, furnished with a 
single definite aperture at its apex, and presenting an appearance of irregular divisions 
into triangular segments, which might easily be supposed to be “ valves ” bounding a 
single undmded cavity. On breaking into the interior of the shell, however, it imme- 
diately becomes apparent that the foregoing resemblance is superficial only ; the entire 
cavity of the shell being divided into numerous chambers, which are completely separated 
from each other by septa, whose lines of junction with the external wall (indicative of the 
successional additions which the shell has received) give rise to the appearance of valvular 
divisions. And a closer examination reveals that these chambers are disposed upon a 
spiral type, each whorl completely investing (save on the adherent base) that which 
preceded it, so that only the external wall of the last whorl is anywhere seen on the 
surface. In the specimen represented in fig. 5, which is one of the isolated individuals 
occurring on the valve of a Pecten, the shell has a much less regular form, owing to the 
more or less complete divergence of the basal portions of the chambers of the last whorl, 
and the partial subdivision of some of those chambers into lobes which exhibit the like 
divergence. The shelly surface of the wall of each chamber presents a somewhat 
areolated aspect, which depends upon its being raised into a multitude of low rounded 
elevations (fig. 8) ; and under a suificient magnifying power these areolae are seen to be 
pretty uniformly marked with minute punctations (fig. 6). The form of the aperture at 
the summit of the cone, of which two examples are shown in figs. 13 & 14, presents a 
striking resemblance to that of the aperture of the Milioloid Foraminifera. 
* Proceedings of the Zoological Society, April 27, 1858. 
