THE NAUTILUS. 69 



Maryland, issued under his direction, are widely used by con- 

 chologists interested in fossil mollusks. This series of reports 

 will be his enduring memorial. Professor Clark' s chief paleon- 

 tological interest was in the Echinoldea, upon which he pub- 

 lished several monographs. 



PUBLICATIONS RECEIVED. 



A Monograph of West American Melanellid Mollusks. 

 By Paul Bartsch (Pro. U. S. Nat. Museum, Vol. 53, pp. 295- 

 356, pis. 34-39, Aug. 1917). This completes the discussion of 

 the West American mollusks of the super-family Pyramidel- 

 loideae, 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 im- 

 bedded." 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 illustra- 

 tions are excellent. 



New and Little Known Species of South American Mus- 

 sels OF THE genus Diplodon. By William B. Marshall (Proc. 

 U. S. Nat. Museum, Vol. 53, pp. 381-388, Pis. 50-55, August, 

 1917). Two new species Diplodon felipjjonei and D. foi-iis are 

 described and figured, together with six species described by 

 Mr, C. T. Simpson in his Descriptive Catalogue of the Naiades 

 and not previously figured. 



Notes on the Shells of the Genus Epitonium and its 

 Allies of the Pacific Coast of America. By William H. 

 Dal!, (Proc. U. S. Nat. Museum, Vol. 53, pp. 471-488, August, 

 1917). An interesting account of the various groups and sub- 

 genera is followed by descriptions of forty-two new species. 



The name Pictoscala is proposed for a section, type Scalaria 

 lineata Say. 



