WES'l' AMKHICAN I'VH A M I DKLIJ I) iMOLLISlvS. 29 



Subgenus TURBONILLA Kisso, n. s. 



Turhonilla Risso, Hist. Nat. Eur. JMer., V(j1. 4, i82(j, p. 224. Type, Turhonilla 

 plica/a Risso. -\-Euturbonilla Semper (part), Arch. Nat. Fr. Meek., 1861, pp. 

 354-361. No type. +ElusaA. Adams, Ann. Mag. Nat. Hist., 3d ser., vol. 6, 

 1861, p. 297. Type, Elusa teres A. Adams. 



Turbonilltis without spinil 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. Usually both ribs 

 and intercostal 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. — Turhonilla tijjnca Dall and Bartsch= T. plicata Risso, 1826, 

 not Turbo plicatus Brocchi, LSI 4. 



KEY TO THE SPECIES OI" THE SUBGENTTS TURBONFLLA. 



Whorls with a low rounded cord at the periphery. 



Whorls strongly contracted at the suture {/ifJi, p. 29. 



\\'horls not strongly contracted at the sutures delmonfensis, p. 30. 



Whorls without a cord at the periphery. 



Summit of the whorls strongly tabulated cenlrola, p. 30. 



Summit of the whorls not tabulated. 



Intercostal spaces and ribs marked by fine crinkly axial sculpture, .ima, p. 31. 

 Intercostal spaces and ribs not marked by fine crinkly axial sculpture. 



Whorls overhanging ,. . diegensis, p. 31. 



WTiorls not overhanging. 



Shell large (adult 10 mm.) acra, p. 32. 



Shell small (adult 6 mm. or less). 



Axial ribs of penultimate whorl 30 lurana, p. 32. 



Axial ribs of penultimate whorl 22 jjroloiu/aln, p. 33. 



TURBONILLA (TURBONILLA) GILLI Dall and Bartsch. 



•• Plate 2, fig. 8. 



Turhonilla {Turhonilla) gilli Dall and Bartsch, Proc. U. S. Nat. Mus., vol. 33, 

 1907, pp. 493, 494, pi. 14, 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 deeply channeled suture decidedly coronated. Inter- 

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

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

 last whorl beyond which they reappear. Base strongly contracted, 

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



