Its relations to modern animals of its type have been very clearly defined by Dr. Carpenter. In the structure of its proper wall and its fine parallel perforations, it resembles the _Nummulites_ and their allies; and the organism may therefore be regarded as an aberrant member of the Nummuline group, which affords some of the largest and most widely distributed of the fossil Foraminifera. This resemblance may be seen in Fig. 11. To the Nummulites it also conforms in its tendency to form a supplemental or intermediate skeleton with canals, though the canals themselves in the arrangement more nearly resemble Calcarina, which is represented in Fig. 12. In its superposition of many layers, and in its tendency to a heaped up or acervuline irregular growth it resembles _Polytrema_ and _Tinoporus_, forms of a different group in so far as shell-structure is concerned. It may thus be regarded as a composite type, combining peculiarities now observed in two groups, or it may be regarded as representing one of these in another series. At the time when Dr. Carpenter stated these affinities, it might be objected that Foraminifera of these families are in the main found in the modern and Tertiary periods. Dr. Carpenter has since shown that the curious oval Foraminifer called _Fusulina_, found in the coal formation, is allied to both Nummulites and Rotalines; and Mr. Brady has discovered a true Nummulite in the Lower Carboniferous of Belgium. I have myself found small Foraminifera in the Silurian and Cambro-Silurian of Canada. This group being now brought down to the Palæozoic, we may hope to trace it to the Primordial, and thus to bring it still nearer to Eozoon in time. [Illustration: Fig. 12.--Portion of shell of Calcarina. Magnified, after Carpenter, (_a_) Cells. (_b_) Original cell wall with tubuli. (_c_) Supplementary skeleton with canals.]