548 
I)R. carpenter's researches on the FORAMINIFERA. 
however, serve only to give a general idea of the diversities of external conformation 
which had presented themselves to him ; and notwithstanding their number and 
variety, they do not include some of the most important among the protean shapes of 
these bodies, nor do they throw any light upon their internal structure. 
80. The memoir of Professor Ehrenberg"^, in which his group of Bryozoa was 
originally constituted, contains the first recognition of the relationship between 
Orhitolites (5[ 4) and Orbiculina ; of which the first had previously been ranked 
among the Zoophytes ; while the second (until the Rhizopodous nature of the whole 
group of Foraminifera was made known by M. Dujardin in 1835) had been associated 
with the Cephalopods. Professor Ehrenberg's description and figures of OrhicuUna, 
however, being just as inaccurate as I have shown those of Orhitolites to be (partly, 
it seems likely, through his unacquaintance with the mode of making thin sections), 
there is no occasion for me to make further reference to them. 
81. The excellent memoir of Professor WiLLiAMsoN-j- “ On the minute structure of 
the Calcareous Shells of some recent species of Foraminifera,” contains the first 
approach to a correct description of the internal conformation of Orbiculina', and 
the fact was fully recognized by him, that in advanced age, when the spiral type of 
growth has given place to the cyclical, there is no other difference between the 
structure of Orhitolites and that of Orbiculina, than that which arises from the dis- 
similarity of their earlier mode of development. Although I am satisfied that, as to 
one or two points of minute structure. Professor Williamson has fallen into error, I 
am disposed to attribute this to the want of a sufficient number of well-preserved 
specimens for examination ; and for having it in my power to correct and extend his 
description, I am chiefly indebted to Mr. Hugh Cuming, the specimens of this type 
included in his Philippine collection being remarkable both for their high develop- 
ment, and for their very beautiful state of preservation. 
82. The investigations of Professor Williamson are entirely unnoticed by M. 
d’Orbigny in his latest classification of the Foraminifera Orbiculina being ranked 
in the Qv(\ev Helicostegues, and being defined as follows, — “ Coquille nautiloide, eom- 
primee, formee de loges divis^es interieurement en compartiments reguliers, percees 
de nombreuses ouvertures en lignes longitudinales a I’enroulement special — whilst 
Orhitolites (his definition of which has been already cited, ^ 5) is placed in the order 
Cyclostegues. The separation of the two genera by so wide an interval, is grounded, 
therefore, on the assumption that the type of growth in OrhicuUna is spiral, whilst 
that of Orhitolites is cyclical. I have already shown that this assumption is incorrect 
as regards Orhitolites, the early plan of whose growth is frequently spiral (^ 54); and 
I shall presently show that it is equally incorrect as regards Orbiculina, whose later 
plan of growth is typically cyclical. And after having closely compared these and 
* Transactions of the Royal Academy of Berlin* 1839. 
t Transactions of the Microscopical Society, 1st series, vol. iii. p. 120. 
X Cours Elementaire de Paleontologie, tom. ii. Paris, 1852. 
