Only as yet on the coast of Labrador and neighbouring parts of North America, and in rocks that were formed in seas that washed the old Laurentian rocks, in which Eozoon was already as fully sealed up as it is at this moment, do we find Protozoa which can claim any near kinship to the proto-foraminifer. These are the fossils of the genus _Archæocyathus_--"ancient cup-sponges, or cup-foraminifers," which have been described in much detail by Mr. Billings in the reports of the Canadian Survey. Mr. Billings regards them as possibly sponges, or as intermediate between these and Foraminifera, and the silicious spicules found in some of them justify this view, unless indeed, as partly suspected by Mr. Billings, these belong to true sponges which may have grown along with Archæocyathus or attached to it. Certain it is, however, that if allied to sponges, they are allied also to Foraminifera, and that some of them deviate altogether from the sponge type and become calcareous chambered bodies, the animals of which can have differed very little from those of the Laurentian Eozoon. It is to these calcareous Foraminiferal species that I shall at present restrict my attention. I give a few figures, for which I am indebted to Mr. Billings, of three of his species (figs. 38 to 40), with enlarged drawings of the structures of one of them which has the most decidedly foraminiferal characters. [Illustration: Fig. 38. _Archæocyathus Minganensis--a Primordial Protozoon._ (_After Billings._) (_a._) Pores of the inner wall.] [Illustration: Fig. 39. _Archæocyathus profundus--showing the base of attachment and radiating chambers._ (_After Billings._)] [Illustration: Fig. 40. _Archæocyathus Atlanticus--showing outer surface and longitudinal and transverse sections._ (_After Billings._)] [Illustration: Fig. 41. _Structures of Archæocyathus Profundus._ (_a._) Lower acervuline portion. (_b._) Upper portion, with three of the radiating laminæ. (_c._) Portion of lamina with pores and thickened part with canals. In figs. _a_ and _b_ the calcareous part is unshaded.]