316 CALIFOllNIA ACADEMY OF SOIENCF^. 



anterior portion of tliu bociy-wliorl. Tlio uppLr whorls iire more coiivrx and iiiore 

 (listiiictly sepanitcd from each other l)y tlie suture than are the U|)per whorls of the 

 hitter species. All the specimens t'diiiHl wore larger than the average N. recluziana, 

 some of them being over 100 nun. in altitude. 



Rare in the upper San Pnlro series of 8an Peilro, Los Cerritos, Long Beach, 

 Cniwlisli (ieorge's, and Deadman Island. The specimen figured is from the upper 

 San Pedro series at San Pedro, and is now in the collection of J)elos 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 niiiuite spire and very large aperture; e.xternally with revolving striae; 

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

 subspiral. 



Sigaretus neritoideus Liun. is a characteristic species. 



356. Sigaretus debilis Gould. 



Sigaretus debilis Gld., Jour. Bo.st. 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. Rept. 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 striae, much finer on the ventral than on the dorsal surface." 



Dimensions. — Length about 22 mm. 



The above is Gould's original description. 



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

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



Living. — Monterey to Lower California (Cooper). 



Pleistocene. — San Pedro (Arnold). 



Pliocene. — San Diego well (('ooper). 



