316 CALIFOKNIA ACADEMY OF SCIENCES. 



anterior portion of the body-whorl. The upper whorls are more convex and more 

 distinctly separated from each other by the suture than are the upper whorls of the 

 latter species. All the specimens found were larger than the average N. recluziana, 

 some of them being over 100 mm. in altitude. 



Rare in the upper San Pedro series of San Pedro, Los Cerritos, Long Beach, 

 Crawfish George's, and Deadman Island. The specimen figured is from the upper 

 San Pedro series at San Pedro, and is now in the collection of Delos Arnold. 



Living. — Straits of Fuca to San Diego (Cooper): Japan (Tryon): Catalina 

 Island (Arnold). 



Pleistocene. — Santa Barbara; San Nicolas Island (Cooper) : San Pedro (Arnold). 



Pliocene. — Kirker's Pass; Santa Barbara; San Fernando (Cooper) : Soquel, 

 Santa Cruz County (Arnold). 



Genus Sigaretus Lamarck. 



Shell ear-shaped, with minute spire and very large aperture; externally with revolving striae; 

 color usually white, with sometimes a thin, corneous epidermis. Operculum minute, horny, 

 subspiral. 



Sigaretus neritoideus Linn, is a characteristic species. 



356. Sigaretus debilis Gould. 



Sigaretus debilis Gld., Jour. Bost. Soc. Nat. Hist., Vol. VI, 1853, p. 379, PI. XIV, fig. 17. Cpr., 

 Proc. Zool. Soc, 1856, p. 207. Tryon, Man. Conch., Vol. VIII, p. 57, PI. XXIV, 

 fig. 65, 1886. Cooper, 7th Ann. Rapt. Cal. St. Min., 1888, p. 264. Keep, West Coast 

 Shells, p. 47, 1892. 



"Shell small, much depressed, thin, almost pellucid; whorls two, spire almost coincident 

 with the general surface; apex at one-fourth the diameter of the shell; periphery obtuse-angular, 

 becoming more so as it approaches the aperture; ventral surface excavated at the umbilical region, 

 with a slight unappressed lamina at that point; margin of the aperture having a very slight advance 

 in the outline, as it approaches the peripheral angle; surface with very numerous and very delicate 

 obtusely excavated revolving striee, much finer on the ventral than on the dorsal surface." 



Dimensio7is. — Length about 22 mm. 



The above is Gould's original description. 



Rare in the upper San Pedro series; one imperfect specimen from that hori- 

 zon at Los Cerritos, and one nearly perfect one from the lumber yard, San Pedro. 



Living. — Monterey to Lower California (Cooper). 



Pleistocene. — San Pedro (Arnold). 



Pliocene. — San Diego well (Cooper). 



