N0.1574. WEST AMERICAN PYRAMIDELLTD.E— BALL AND BARTSCH. 493 



The following 6 of the 23 recognized subgenera are represented in 

 the present faunal area: TurhoniUa s. s., Chemnitzia^ StrloturhoniUa^ 

 Pyrgolan(pro.% Pyrgiscv.s, and Morwvla. 



KEY TO SUBCiENERA OF TURBONILLA. 



Shell with spiral sculpture: 



Varices present Morm iila p. 510. 



Varices absent. 



Spiral sculpture consisting of many very tine incised striations. 



Aperture subquadrate StrioturhunJIla v. 495. 



Aperture oval Pyrgolamproa p. 498. 



Spiral sculpture consisting of strong, incised spiral grooves. .Pynjisciiii p. 504. 

 Shell without spiral sculpture: 



Ribs interrupted at the periphery Chemnitzia p. 494. 



Ribs continuing over the base Tarbomlla p. 493. 



Subgenus TURBONILLA Risso, s. s. 



TurhonUla Risso, Hist. Nat. Eur. Mer., IV, 1826, p. 224; =EutnrhonUla Semper 

 (part), Arch. Nat. Fr. Meek., 1861, pp. 354-361. 



Turbonillas without spiral sculpture, having prominent vertical ribs 

 which extend from the summits of the whorls to the umbilical region; 

 the same is true of the intercostal spaces. Usuall}" both ribs and inter- 

 costal spaces are less strongly defined on the base, below the periphery, 

 than on the exposed portion of the whorls above it. Columella straight 

 or slightly twisted. All our West Coast forms belonging to this 

 subgenus are small and slender, of semitranslucent bluish-white to 

 milk-white color. 



Type. — TarhonlUd typica Dall and Bartsch, T. iMcata Risso, 1826, 

 not Turbo plicat us Rrocchi, 1814. 



TURBONILLA (TURBONILLA) GILLI, new species. 



Plate XLIV, fig. 5. 



Shell small, rather stout, inflated, dirty white. Nuclear whorls 

 decollated, early post-nuclear whorls well rounded, later ones flat, 

 broader at the summit than at the suture; sculpture of about fourteen 

 strong, almost vertical, scalariform axial ribs on the second, and six- 

 teen quite protractive ones on the succeeding whorls; on the penulti- 

 mate turn, however, they are less oblique than on those preceding it. 

 These ribs are very strongly developed at the summit of the whorls 

 and render the deepl}^ channeled suture decidedly coronated. Inter- 

 costal spaces deep, of about double the width of the ribs, interrupted 

 suddenly at the decidedly angulated (almost keeled) periphery of the 

 last whorl beyond which the}^ reappear. Base strongly contracted, 

 quite short, marked by the faint continuations of the axial ribs which 

 extend to the umbilical region. Outer lip fractured; aperture? col- 

 umella very strong, somewhat curved and revolute, provided with a 

 subobsolete oblique fold. 



