AKNOLD — THE PALEONTOLOGY AND STKATIGRAPHY OF SAN PEDKO. 235 



portion of aperture ridjred by spiral sculpture; outer lip thin; inner lip thinly incrusted; columella 

 twisted and spirally ornamented; groove on upper part of columella prominent; canal short, curved. 

 Dimensions. — Long. 23 mm.; lat. 12.3 mm.; hocly-whurl 15 mm.; aperture, including canal, 

 II mm.; doll. 40 degrees. 



The transverse oriKunoiitiilioii i.s tlie luu.st proniiiient in the iii»[>er wliorls, 

 while in the hiter ones the spiral ridjjjes are the most iiiii)ortant. On the body-whorl 

 the lranver.se ri(l<;;es sometimes become nciirly obsolete, beinj^ represented only by 

 lines of fj;rowth. 



Common in the upper and rare in the lower Ran I'ech'O .series at .San Pedro 

 and vicinitv. Also fonnd in the Pliocene at Deadman Island and Timiu's Point. 

 Found in the Pleistocene at Sjiaiiish P>ight and Pacific Beach, San Diego; and at the 

 old irri;;ating ditch and Barlow's raiicli, Ventura. 



Living. — San Francisco to San Diego; Lower California (Cooper). 



Pleistocene. — Santa Barbara to San Diego (Cooper): San Pedro; Ventnra; 

 San Diego (Arnold). 



Pliocene. — San Diego well (Dall): San Pedro (Arnold). 



Miocene. — Santa Monica and Aliso Creek, Los Angeles Connty (Cooper). 



225. Nassa tegula Reeve. 



Nassa tegula Rye., Icon. Conch., Nassa, No. 98, PI. XV, 1853. Cpr., Brit. Assn. Rept., 1863, 

 p. 662. Gabh, Pal. Cal., Vol. II, p. 74, 1869. Trvon, Man. Conch., Vol. IV, p. 39, 

 PI. XIII, tigs. 166, 167, 1882. Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 253. 

 Keep, West Coast Shells, p. 37, fig. 17, 1892. Dall, Proc. U. S. Nat. Mus., Vol. XV, 

 1892, p. 213. 



Shell small, conical; spire elevated; apex subacute; whorls five, slightly angulated at middle, 

 with nine or ten prominent transverse ridges most prominent on angular part of whorl; these ridges 

 are sometimes divided by spiral grooves into two or more nodes; suture impressed, distinct; aper- 

 ture subquadrate; outer lip thickened by a row of elongated denticles; inner lip smooth and incrusted, 

 the incrustation spreading over the columella and the front of the shell like an apron; a rather shallow 

 groove separates the lower portion of columella from body- whorl; canal very short. 



Dimensio7ts. — Long. 11 mm.; lat. 7 mm.; body-whorl 7.9 mm.; aperture, including canal, 

 5 mm.; defl. 58 degrees. 



The most robnst of the Nat^sas found in this locality. Distinguishable by 

 the prominence of the incrustation on the inner lip. Dr. Dall says that this species 

 is close to N. vibex of the Atlantic coast. 



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

 Deadman Island, and Crawfish George's; also occasionally found in the lower San 

 Pedro series at Deadman Island and San Pedro. Found also in the Pleistocene at 

 Twenty-sixth Street and Sj)anish Bight, San Diego. 



Living. — Santa Barbara to San Diego; Lower California (Cooper). 



Pleistocene. — Santa Barbara to San Diego (Cooper): San Pedro; San Diego 

 (Arnold). 



