It differs from _Urolophus_, as described by Richardson, in the upper velum of mouth being entire, and in having about twenty small tubercles on the surface of lower velum. These however can scarcely be considered generic differences. Found abundantly in muddy creeks at San Pedro and San Diego, those from the former place being more uniform in color. While I was at San Diego the little son of Major G. O. Haller, U. S. A. was wounded in the foot, probably by one of these fish, while wading along a muddy shore of the bay. The wound was very painful for some hours, though small. Another large rhomboidal species also abundant there but apparently still undescribed, inflicts very severe and dangerous wounds, of which I may have more to say hereafter. This fish has great muscular power and can dart very rapidly through the water by lateral vibrations of its tail, at the same time quickly flapping the edge of its disk, to keep its level in the water and to regulate its direction. It frequently buries itself slightly under the mud, and if disturbed obscures the water by stirring the mud, vanishing in the cloud thus raised to hide itself again. It will allow a boat to pass over its place of concealment, and may, if detected, be easily killed by a blow with the end of an oar. Many are also caught in the seines of the fishermen. Their food consists of small mollusca, crustacea and such other animals, alive or dead, as they can obtain. REGULAR MEETING, DECEMBER 7TH, 1863. President in the Chair. Present, ten members. Donations to Cabinet: Rock Salt, from the Upper Colorado River, by F. Ailing. Wood, from near Carson City. Dr. Cooper stated that he had received a communication from Mr. P. P. Carpenter, of England, offering to describe any new species of shells from the collections of the State Geological Survey or of the Academy, and to publish the descriptions in its proceedings. The Society accepted the proposition. Two new sheets of the Proceedings were laid upon the table. REGULAR MEETING, DECEMBER 21ST, 1863. President in the Chair. Present, seven members. Messrs. Royal Fisk and R. L. D’Aumaile were elected resident members. [Illustration: FIG. 22. OPHISURUS CALIFORNIENSIS—Garrett. [Described on p. 66 of this volume.]] ANNUAL MEETING, JANUARY 4TH, 1864. President in the Chair. Fifteen members present. E. Mathewson, Esq., of Martinez, was elected resident member. The following is an abstract of the Annual Reports of the officers of the Society, for the past year (1863): The Financial Report of the Trustees was received and accepted. During the year, $815.35 have been received from various sources, besides the balance on hand from 1862, of $141.22; $903.75 expended; and $52.82 remains in the hands of the Treasurer.