This very minute species—often barely an inch or more in height—had hitherto escaped our observation, until little friend George Bloomer discovered it, while on a trip with us to the hills in this vicinity. The whole plant at length often assumes a scarlet or purplish hue. It certainly is not the _C. violacea_ of D. C. and appears quite as distinct as any species known to us. Mr. Bolander made some remarks on the peculiar growth of _Carex decidua_, in Marin County, not on the borders of the creeks, but in the middle of them. He also spoke of _Hierochloa fragrans_ R. S., as a remarkably fragrant plant, and as furnishing beautiful grass for lawns. REGULAR MEETING, MAY 18TH, 1863. President in the Chair. Nine members present. Messrs. W. S. Sullivant, and Leo Lesquereux, of Columbus, Ohio, were elected Corresponding Members, and Rev. T. Starr King a Resident Member. Donations to the Cabinet were received as follows: Specimens of copper ore from the Mammoth Lode, Del Norte County, by Dr. Trask. REGULAR MEETING, JUNE 1ST, 1863. President in the Chair. Ten members present, and Dr. Hillebrand, of Honolulu, by invitation. Dr. Kellogg presented the following paper: Description of a New Species of Hosackia. BY A. KELLOGG, M.D. HOSACKIA Dougl. _H. argentea_ Kellogg. [FIG. 8.] [Illustration: FIG. 8.] Appressed satiny pubescent throughout, prostrate, much branching from a perennial crown. Leaves short, very densely set or crowded along the lower stem, leaflets three, very small, rounded, and scarcely mucronate; the upper leaves larger, leaflets four (only one of the lower pair developed), obovate obtuse, very abruptly mucronate-acute; stipules red, minute and gland-like, glabrous. Peduncles twice the length of the leaves; umbels six to ten-flowered, bract of a single sessile obovate leaf (a few separate pink glands or embryoid stipules often present). Flowers orange yellow throughout; keel obtuse, wings and banner equal; teeth of the calyx about one-third its length, acuminate, embryo legume terete, appressed pubescent, two-seeded; mature fruit unknown. From Kern River, pendent from rocky cliffs. The Society is indebted to Mrs. Hutchings for this new and very beautiful species. Dr. Ayres presented a paper by Dr. T. M. Logan, of Sacramento, on the Physics, Hygiene, and Thermology of the Sacramento River, which was read and referred to the Publishing Committee. REGULAR MEETING, JUNE 15TH, 1863. Dr. Ayres in the Chair. Six members present. Donations to the Cabinet: Insects from seeds imported from Germany, by Mr. Bevans; plants from Sonoma, by Dr. Behr. Donations to the Library: Annual Report of the Trustees of the Museum of Comparative Zoology for 1862. American Journal of Science for May, 1863, from the Editor. Dr. Kellogg read the following paper: Description of a New Species of Mentzelia.