A NEW MOLLUSK OF THE GENUS MACROMPHALINA 

 FROM THE WEST COAST OF AMERICA. 



By Paul Bartsch, 



Assistant Curator, Dirisioii of MoUiisls, II S. National Museum. 



While examining- a series of small West American shells in the 

 collection of the United States National Museum, two specimens of a 

 new Macromplialina were found. That species is here described and 

 figured. 



MACROMPHALINA OCCIDENTALIS, new species. 



Shell verj^ small, broadly conic with moderately elevated spire, 

 white. Nepionic whorls 2, exceedingly small, smooth and glassy, 

 forming the almost spherical apex. Succeeding turns decidedly 

 inflated, well rounded above, 

 marked by man}" tine incre- 

 mental lines and numerous 

 still finer spil'al lines, which 

 are equal in strength and 

 closely, equally spaced. 

 Sutures deeply channeled. 

 Last whorl bluntly angu- 

 lated at the periphery . Base 

 very wide and only mod- 

 erately rounded, with the umliilical area broadly excavated, marked 

 like the upper surface. Aperture patulous, ovate, the columellar 

 wall forming the narrow end of the oval; outer lip thin, decidedly 

 expanded; columella slender and gently curved; parietal wall very 

 small, covered by a very thin callus, which renders the peritreme 

 almost complete. 



The type has Sf whorls and measures: Greater diameter 1.7 mm.; 

 lesser diameter 1.2 mm.; altitude 1.3 mm. 



The type and another specimen were collected at Point Abreojos, 

 Lower California, and form Cat. No. 126965 of the U. S. National 

 Museum collection. 



MACROMPHALINA OCCIDENTALIS. a, SIDE VIEW; h, BASAL 

 VIEW. 



Proceedings U. S. National Museum, Vol. XXXII— No. 1522. 



233 



