Botany and Zoology. 431 
The author then points ee what may be gathered oe observation 
and from deduction respecting the Nutrition and mode of Growth of 
these creatures. e shows that the former is probably: rtp = te 
plete annulus, thickened at intervals into segments, and narro tar: ei 
tween these into connecting stolons, the shell being probably produced 
by the sSpenineee of their outer portions. And this view he supports 
by the results of the examination of a number of specimens, in which 
reparation ony injuries has taken place. Regarding the Reproduction 
of Orbitolites, he is only able to suggest that certain minute spherical 
masses of sarcode, with which some of t e cells are filled, may be 
nothing save essen aa of tis: naiiaaiee in their living state can give 
Satisfactory result 
he regular He of structure just described is subject to numerous 
variations, into a minute description of which the author next enters; 
the general results being, that neither the shape nor dimensions of the 
entire disk, the size of the nucleus or of the cells forming the concen- 
trie zones, ‘the surface-markings indicating the shape of the superficial 
cells, nor the early mode of growth (which, though typically cyclical 
oe €s approximates to a spiral), can serve as as distinctive charac- 
rs of species; since, whilst lie are all found to present most re- 
ae differences, these differe es, being strictly gradational, can 
only be considered as duinguishing alia iduals. It thus — ser 
4 very wide range of variation exists in this type ; ; So that 
Afier noticing some curious monstrosities, resulting from an unusual 
Outgrowth of the central nucleus, the author p to inquire into 
essential character of the Orbitolite, si its relations to other types 
of structure. He e places it among the very lowest forms of Foramin- 
ifera ; and considers that it approximates closely to sponges, some o 
which heres skeletons not very unlike ove calcareous net-work which 
intervenes between its fl leshy segments. Of the species which the 
genus has been reputed to include, he states that a large proportion 
