NO. 220T. WEST AMERICAN MELANELLID MOLLVSKS—DARTSCE. 301 



in the Temblor Basin, California, and Neocene Deposits of the San 

 Juan District, San Louis Obispo County.' Here the following are 

 described and figured: Niso (?) antiseUi Anderson and Martin, p. 

 65, pi. 7, fig. 22, and Eulima gahhiana Anderson and Martin, p. 68, 

 pi. 7, fig. 20, the last being a Melanella. 



The group covered by the present monograph is by far the most 

 difficult one that I have thus far treated; the characters are few and 

 confined in the different groups chiefly to differences in outUne, 

 flexure, size, weight, and in addition to these, in the case of Stromhi- 

 formis and Niso, to color patterns. Whatever there may be of merit 

 in this study, I feel that the credit for it should fall upon the collectors 

 and institutions that have placed all their material in my hands, for 

 without this abundance of material, it would have been entirely 

 impossible to reach the positive conclusions expressed in these pages. 

 Foremost among these I wish to express my thanks to Dr. H. A. 

 Pilsbry, of the Philadelphia Academy of Natural Sciences, for the 

 loan of types, and to Prof. F. B. Loomis of Amherst College, for the 

 loan of C. B. Adams's types from Panama. Also to the California 

 Academy of Sciences for similar favors and the Stanford University 

 for the loan of specimens. Of the private collectors, the material 

 submitted by Mr. and Mrs. T. S. Oldroyd leads easily, both as far as 

 number of species and specimens are concerned. These collections 

 are followed by those of Miss J. M. Cooke; Mrs. Kate Stephens; Dr. 

 Frank Baker; Dr. Ralph Arnold, whose collection is particularly rich 

 in fossil material; Dr. S. S. Berry; Prof. F. W. Kelsey; Mr. F. L. 

 Button; Mrs. Elizabeth E. Johnston; Mr. H. N. Lowe; Mrs. Paula 

 Ball; Mrs. W. H. Eshnaur; and Mrs. Maria Baldridge. It should 

 also be here stated that the splendid collections made by the late 

 Mr. Henry Hemphill and the late Mr. C. W. Gripp, now in other 

 hands, have materially added to the knowledge of these forms. 



This paper would be incomplete, did I fail to express my apprecia- 

 tion to Dr. William H. Dall, honorary curator of the section of 

 Mollusks, for his kindly counsel and encouragement while working on 

 this difficult problem. 



The photographs used in the illustrations were mostly made by Mr. 

 T. W. Smiffie, of the United States National Museum. A few were 

 taken by Mr. John H. Paine, and all of them were retouched by Mrs. 

 E. B. Decker, under ray personal supervision. 



KEY TO THE WEST AMERICAN QENEEA AND SUBGENERA OF THE FAMILY. 



Shell umbilicated Niso, p. 348. 



Shell not umblilicated. 



Nuclear whorls forming a mucronate apex. 



Postnuclear whorls globular Stilifer, p. 352. 



Postnuclear whorls not globular. 



Postnuclear whorls oval Lamberlia, p. 354. 



Postnuclear whorls cylindric Mucronalia, p. 353. 



« Proc. Cala. Acad. Scl., ser. 4, vol. 4, 1914. 



