552 
DR. carpenter’s RESEARCHES ON THE FORAMINIFERA. 
having many such floors, with numerous rows of marginal pores. In the former, the 
segments of sarcode, with their single annular stolon, would resemble rounded beads 
strung at short distances on a cord. In the latter the segments would be columnar, 
with constrictions at intervals, and would communicate with each other by two or 
more annular stolons.^ — It is true that we seldom find any such complete differentia- 
tion of the superficial cells, as the fully-developed type of Orbifolites presents ; but 
we have seen that such differentiation is by no means a constant character in that 
genus 58); and the structure of the most developed specimens I have examined 
among the recent Orhiculince closely corresponds in this respect with that of the 
fossil OrbitoUtes of the Paris basin, as will be seen on comparing the left-hand portion 
of Plate XXIX. fig. 3 with Plate VI. fig. 1 1 of my former memoir. But it is not' a 
little remarkable, that while the fossil OrbitoUtes of the Paris tertiaries are less deve- 
loped in this respect than their existing repi’esentatives in the South Seas, the fossil 
Orbiculinte of the Malabar tertiaries should be more developed than existing speci- 
mens of the same type ; for in them we find the superficial cells differentiated from 
the intermediate layers (Plate XXVIII. fig. 20), precisely as in OrbitoUtes^. Looking 
to the far larger dimensions, as well as to the higher development, which these fossils 
present 83), as compared with the existing specimens of OrbicuUna, I am disposed 
to believe that this type attained its highest evolution in a period long since passed, 
and that we now have, so to speak, only the degenerate descendants of an ancestry of 
higher rank; whilst in the case of OrbitoUtes, I am inclined to think that the type is 
most fully evolved at the present time. 
91. General conclusion. — From the foregoing details it is obvious that the relation- 
ship between OrbitoUtes and OrbicuUna is extremely close ; the only essential point 
of difference between them being that which is furnished by the structure of the 
nucleus. Whether or not they ought to rank as types of distinct genera, or whether 
they ought (as Professor Williamson maintains) to rank as cognate species of the same 
genus, is a point as to which it is impossible to arrive at a satisfactory conclusion, 
until the characters which should serve for the distinction of genera and species in 
this class shall have been determined on a physiological basis. This much I think 
myself entitled to assert with confidence, — that even if they are to be regarded as 
distinct genera, they must be ranked in the same family, and in immediate proximity 
to each other; and that no classification can have any claim to be considered as 
natural, in which they shall be widely separated. 
Genus Alveolina. 
92. History. — Although the form and aspect of the Foraminifera which are refer- 
able to this genus, would seem to remove them altogether from proximity to the pre- 
* Although Mr. Carter has described this fossil as a species of OrbitoUtes, yet it is really an OrbicuUna, as 
is shown by the spiral conformation of its central portion (Plate XXVIII. fig. 17), and by the investment 
afforded by each turn of the spire to its predecessor, as shown in fig. 1 8. 
