28 BULLETIN 68, UNITED STATES NATIONAL MUSEUM. 



The type (Cat. no. 43, Orig. no. (228) A. 3111) is in the State 

 Museum at Albany, New York. It is said to have been collected at 

 Santa Barbara, California, which we consider doubtful. It seems 

 more likely that it came from the Gulf of California. It has ten post- 

 nuclear whorls and measures: Length 11.6 mm., diameter 4.4 mm. 

 The Academy of Natural Sciences, Philadelphia, has a specimen (Cat. 

 no. 57870), collected by Colonel Jewett, at Mazatlan, Mexico, which 

 has eight whorls and measures: Length 9.8 mm., diameter 4 mm. 

 It is this specimen which has served for our figure. 



Genus TURBONILLA Risso. 



Turbonilla Risso, Hist. Nat. Eui\ Mer., vol. 4, 1826, p. 224; Euturhonilla Semper, 

 Arch. Nat. Fr. Meek., 1861, pp. 3.54-361. No ty^e-\-Elusa A. Adams, Ann. 

 Mag. Nat. Hist., 3d ser., vol. 6, 1861, p. 297. Type, Elusa teres A. Adams. 



Shell with sinistral apex, cylindro-conic, many whorled, generally 

 slender; with a single columellar fold which varies in strength and 

 frequently is not visible in the aperture. The sculpture both axial 

 and spiral ranges from obsolete to strongly incised lines or raised 

 lamellae. 



Type. — Turbonilla typica Dall and Bartsch. 



Of the twenty-four subgenera now recognized belonging to this 

 genus, eleven occur on the west coast of America. 



KEY TO THE SUBGEMERA OF TURBONILLA. 



Shell with basal keel Asmunda, p. 129. 



Shell without basal keel. 



Varices present Mnrmuln, p. 1 10. 



Varices absent. 



Spiral sculpture absent, or if present, consisting of microscopic slriations only. 

 Axial ribs strong. 



Axial ribs between the sutures and on the base. . . Turbonilla, p. 29. 



Axial ribs between the sutures only Chemnitzia, p. 33. 



Axial ribs feeble, usually only developed on the early whorls, 



Ptycheulimella, p. 59. 

 Spiral sculpture present, always stronger than microscopic striations. 

 Axial sculpture consisting of well-developed ribs. 



Spiral markings consisting of very fine striations. 



Aperture subquadrate Strioturbonilla, p. 40. 



Aperture suboval Pyrgolampros, p. 59. 



Spiral markings consisting of strongly incised lines. 

 Summits of the whorls strongly shouldered. 



Spiral sculpture consisting of very fine incised lines, 



Pyrgisculus, p. 126. 

 Spiral sculpture consisting of incised grooves and cords of 



about equal strength Dunkeria, p. 120. 



Summits of the whorls not strongly shouldered . . Pyrgiscus, p. 74. 

 Axial sculpture reduced to mere raised threads Careliopsis, p. 130. 



