Mr. Dall made some remarks on the shells which have been collected by various naturalists at and near Monterey. He remarked that he himself had collected in two weeks no less than two hundred and nineteen species, which number, added to forty-four which have been previously reported as occurring there, but which he did not obtain, gives two hundred and sixty-three as the whole number of species of shells now known to have been found at Monterey. Of these were previously obtained only to the south of Monterey, twenty-four; previously obtained only to the north of Monterey, forty-two; previously obtained to north and south, but not at Monterey, twenty-nine; previously obtained at Monterey, one hundred and one; not obtained by Mr. Dall, forty-four; new, or not reported, twenty-three. Collections of shells are greatly needed from points between San Francisco and the mouth of the Columbia river, and also from points between San Diego and Cape St. Lucas, in order to determine questions of geographical distribution. A curious fact was noticed in _Chiton scabra_, of Reeve, which, although belonging to a class of strictly marine animals, was observed clinging to the rocks beyond the reach, except in storms, of the highest spray. That it does not migrate is proved by the fact that, living in nooks and crevices of the rocks, it grows into the very form of the hole in which it lives. Mr. Dall also mentioned that, having visited and thoroughly searched the original locality for _Helix Californiensis_, a small island off Point Cypress, accessible only at low tide, this species was found to be nearly exterminated. A letter received from Dr. Canfield of Monterey since the visit of Mr. Dall, confirms the fact of the extinction. This has been caused apparently by a large millipede, which exists in great numbers, and is extremely voracious. Several of the shells found commonly at Monterey, are identical with others collected during the past season on the coast of Russian North America. Professor Whitney made some remarks on the absence of the Northern Drift formation from the western coast of North America and from the interior of the continent, throughout the region to the southwest of the Missouri River.