302 ■ Parheria and Loftusia. KuS. mS^^^^^^ 
are almost entirely replaced by labyrintliic structure. With, this 
increased development of the labyrinthic structure in the concentric 
lamellae themselves, we find it extending between one lamella and 
another, as an investment to the radial tubes; thus forming 
" radial processes " of a sub-conical form, which occupy a consider- 
able part of what would otherwise be the " interspaces " between 
the successive lamellae. Still every lamella is separated from that 
which invests it (except where brought into connection with it by 
its radial processes) by a system of cavities, which are in free 
communication with each other, and which may be collectively 
designated the interspace system;" and from this system the 
labyrinthic structure of the investing lamella is entirely cut off by 
an impervious wall which bounds it upon its inner side ; whilst its 
cancelli open freely upon the outer side of the lamella, into what, 
when it is newly formed, is the surrounding medium, but, when it 
has itself been invested by another layer, into its "interspace 
system." In the larger of the two non-infiltrated specimens which 
have furnished the materials for the present description, the number 
of concentric layers is 40, and their average breadth about l-65th 
of an inch. 
The Author discusses the mode in which this composite structure 
was formed ; and comes to the conclusion that the production of 
each new layer was probably accomplished by the instrumentality 
of the sarcodic substance, which not only filled the cancelli of the 
preceding layer, but projected beyond it ; that the radial processes 
were first built up like the columns of a Gothic cathedral, and that 
their impervious investing-wall spread itself from their summits, 
so as to form a continuous lamella over the sarcodic layer, in the 
manner that the summits of such columns extend themselves to 
form the arched roof of the edifice ; and that on the floor of the 
new layer thus laid the partitions of the cancelli were progressively 
built up by the agency of the sarcodic substance conveyed to the 
outer surface of that floor through the radial tubes. The author 
further argues, from the analogy of living Foraminifera, that, 
notwithstanding the indirectness of the communication between 
the cavitary system of the inner layers and the external surface, the 
whole of that system (consisting of the labyrinthic structure of the 
successive lamellae, and of the interspaces which separate them) was 
occupied during the life of the animal by its sarcode body. 
The flan of growth in Loftusia is stated by Mr. Brady to 
difler extremely from that of Parheria, whilst its intimate struc- 
ture, on which its physiological condition must have depended, is 
essentially the same ; thus afibrding a conspicuous example of the 
validity of the principle of classification already referred to. This 
difference is indicated by its shape, which closely resembles that 
