MR. ARCHER, of Dublin, who is well known as one of the contributors to Pritchard's “Infusoria,” and a careful observer, has for the last two or three years chronicled in the Proceedings of the Dublin Microscopical Club, published in the Quarterly Journal of Microscopical Science, the occurrence of Radiolarian-like Rhizopods in the moor-pools of Ireland. At the end of last year Dr. Focke, of Bremen, described and figured a few of the same forms, bearing a likeness to some which have been considered as belonging to the genus Actinophrys, or sun-animalcules, of Ehrenberg. Mr. Archer has at length published the description of his new species, with full illustrations in three folding coloured plates. Many of these new fresh-water Radiolarians, like the marine forms which they appear to represent in fresh water, carry siliceous spicules; they are mostly globular, and have a capsule surrounded by protoplasmic matter, which is drawn out into very long and delicate threads or rays, whilst the spicules are aggregated so as to form a loose sort of skeleton. In one large species Mr. Archer found several globular capsules united in one individual (Raphidiophrys). The contents of the capsules are coloured green in some instances, in other species they are red, or colourless. These most interesting animals are found only in moor-pools, and are, therefore, not to be got at by every observer. It is, therefore, very curious that besides Mr. Archer's and Dr. Focke's publications in this year, Dr. Richard Greef, of Bonn, should also have turned his attention to them, without being aware of Mr. Archer's work. In No. 3 of Max Schultze's Archiv for this year, Dr. Greef has a paper and plates, describing some species and genera identical with those of Mr. Archer, who, however, has precedence by some months. The fresh-water Radiolaria, it has been suggested, stand in the same relation to the more exuberant and highly developed marine Radiolaria, as do the fresh-water Hydrozoa represented by Hydra to the much more numerous, more brilliant, and varied marine Hydrozoa. Freshwater Radiolaria.—On some Freshwater Rhizopoda, new or little known. By William Archer. (Quarterly Journal of Microscopical Science, July and October, 1869.)