Prof. Brewer made some remarks on the method of calculating altitudes by observation with a single barometer. He gave an account of the methods adopted by the Geological Survey for computation, in cases where there was no station barometer nearer than the bay, or the valley of the Sacramento. Dr. Trask mentioned that the weight of the Honcut meteoric iron presented by him to the Academy, at the meeting of March 17th, 1862, was six ounces, one hundred and twenty-eight grains, troy. Professor Whitney called attention to the curious errors in a paper published in Petermann’s Mittheilungen, 1861, page 133, which purports to be a translation into German of a portion of a work published by Mr. J. Xantus, describing his journey in Lower California. He describes a quicksilver mine of great importance as being worked at Marques; but the description which he gives of it shows that it is the New Almaden mine which, in reality, he visited, and which, by some confusion of his notes, he has located in Lower, instead of Upper California. No mercury mine is worked on the California peninsula, so far as can be ascertained. It is evident that Mr. Xantus’s notice of rich gold, lead and copper mines on the peninsula must be taken with many grains of allowance. On motion of Dr. Ayres, it was ordered, that twenty-five copies of the second volume of the Proceedings be placed at the disposal of the Publishing Committee for distribution to learned societies, public libraries, and distinguished scientific men in the Atlantic States. REGULAR MEETING, MARCH 2D, 1863. President in the Chair. Present, fifteen members. Dr. J. P. Kirtland, of Cleveland, Ohio, was elected a corresponding member. Donations to the Cabinet. By Mr. Rowlandson, specimen of the wool of the Alpacca and Vicuña, brought from Peru by Capt. Bissell, of the United States sloop-of-war _Cyane_. Donations to the Library. The American Journal of Science, for January, 1863, from the editors. Mr. Gabb communicated two papers by Mr. Rémond, containing descriptions of new fossils from California. Description of two New Species of Bivalve Shells, from the Tertiaries of Contra Costa County. BY AUGUSTE RÉMOND. CARDIUM Brug. _C. Gabbii_ Rémond. Shell cordate, ventricose, nearly equilateral; posterior side truncated, direct; anterior side slightly depressed; height and length nearly equal. Umbones very prominent; beaks incurved, approximate; lunule well marked, carinated; surface even, with fine imbricated lines of growth. Hinge (of the left valve) comparatively narrow; anterior fosset small, shallow, triangular; cartilage pit large, deep, long; lateral teeth heavy, thick, prominent. Locality: vicinity of Kirker’s Pass, south of New York (of the Pacific) Plain from a late tertiary deposit.