WEST AMERICAN PYKAMIDELLID MOLLUSKS. 9 



A' Columellar folds three— Continued. 

 Shell not umbilicated. 



Surface polished, marked only by fine lines of growth and microscopic spiral 

 striations. 



Periphery sulcate. 



Subgenus Longchaeus Morch, 1875 (p. 21). 



Type, Pyramidella punctata Schubert and Wagner. 



Periphery not sulcate. 



Subgenus Voluspa Dall and Bartsch, 1904 (p. 19). 

 Type, Pyramidella auricoma Dall. 



Surface sculptured. 

 Basal cords absent. 

 Periphery sulcate. 



Shell marked by strong axial ribs which terminate at the pe- 

 riphery, and microscopic spiral striations. 

 Subgenus Pharcidella Dall, 1889 (p'. 25). 

 Type, Pharcidella folinii Dall. 



Shell marked by strong spiral keels and weak axial riblets. 

 Subgenus Callolongchaeus Dall and Bartsch, 1904 (2). 

 Type, Pyramidella jamaicensis Dall. 



Periphery not sulcate. 



Shell marked by strong axial ribs, intercostal spaces strongly 

 spirally striated, aperture auricular. 



Subgenus Otopleura Fischer, 1885 (3). 



Type, Pyramidella auris-cati Chemnitz. 



Basal cords present. 



Shell marked by strong spiral ridges, moderately strong axial 

 ribs and two basal cords. 



Subgenus Triptychus Morch, 1875 (4). 

 Type, Triptychus niveus Morch. 

 A- Columellar folds two. 

 Shell umbilicated. 



Surface polished, marked by very fine lines of growth and microscopic spiral 



striations. 



Subgenus Tiberia Monterosato, 1875 (5). 



Type, Pyramidella nitidula A. Adams. 



Surface polished, marked by fine lines of growth and strong spiral striations. 

 Subgenus Ulfa Dall and Bartsch, 1904 (2). 



Type, Pyramidella ( Ulfa) cossinanni Dall and Bartsch 

 z=Syrnola striata Cossmann. 



Surface marked by strong axial ribs, intercostal spaces spirally pitted; early 

 post-nuclear whorls sculptured differently from the later ones. 



Subgenus Tropaeas Dall and Bartsch, 1904 (2). 

 Type, Pyramidella subulata A. Adams. 



Shell not umbilicated. 



Surface polished, marked by very faint lines of growth and microscopic 

 spiral striations. 



Basal fasciole present. 



Subgenus Vagna Dall and Bartsch, 1904 (2). 

 Type, Pyramidella paumotensis Tryon. 



