The conditions of life which obtain now in Waller Creek are those of a new life region. This must of necessity be so in an intermittent stream to a certain extent, but owing to the flood conditions here they are doubly so. The chief facts of interest in regard to the habits of snails as shown by these observations, are these: 1, The snails of both species are to be found commonly in uncontaminated water which is running at a fairly rapid rate, and the most common orientation is with the heads pointing up stream; 2, The snail population in any stream is subject to wide fluctations depending upon flood conditions; 3, Physa because of its shape is less affected by floods than Planorbis; 4, The return of the snail population to a given stream is determined not only by the frequency and severity of the floods, but also by the condition of the bottom of the stream after the subsidence of the high water; 5, The snails thrive best where there is a constantly renewed supply of clean water which contains little decaying vegetation. _Wabash College, Crawfordsville, Ind._ WILLIAM BULLOCK CLARK. Dr. William Bullock Clark, professor of geology in the Johns Hopkins University, eminent for his contributions to geology, died suddenly from apoplexy on July 27, at his summer home at North Haven, Maine. Wm. Bullock Clark was born at Brattleboro, Vermont, December 15, 1860. Since 1894 he was professor of geology in Johns Hopkins University. In 1896 Professor Clark organized the Maryland Geological Society, and has been State Geologist since that time. The admirable volumes on paleontology of Maryland, issued under his direction, are widely used by conchologists interested in fossil mollusks. This series of reports will be his enduring memorial. Professor Clark’s chief paleontological interest was in the _Echinoidea_, upon which he published several monographs. PUBLICATIONS RECEIVED. A MONOGRAPH OF WEST AMERICAN MELANELLID MOLLUSKS. By Paul Bartsch (Proc. U. S. Nat. Museum, Vol. 53, pp. 295‒356, pls. 34‒39, Aug. 1917). This completes the discussion of the West American mollusks of the super-family Pyramidelloideae, comprising the family Pyramidellidae, which has been previously treated, and the Melanellidae here considered. The former are readily distinguished by having the “nepionic whorls sinistral and tilted; the axis of the early whorls usually being at right angles to that of the succeeding turns, in the first of which the nuclear whorls are frequently quite strongly imbedded.” In the latter the early whorls are dextral and never tilted or immersed. A review of the work done in this group is followed by the descriptions of the species, including forty-nine new species and one new genus _Eulimostraca_. The illustrations are excellent. * * * * *