ARNOLD — THE PALEONTOLOCJY AND STUATIGKAl'HY OF SAN PEDRO. 295 



319. Bittium rugatum Carpenler. 



I'LATK IV, Fii:. 11. 



Bittium rugatum Cpr., Ann. iS: \\:\<^. Nat. Hist., 3rci Ser., Vol. XVH, 1866, p. 276. 



Sliell small, turreted; spire elevated; ape.x acute; whorls ten to eleven, flat; numerous trans- 

 verse ridjjes, crossed by a varying number of nearly equally prominent spiral ridges, produce a 

 nodose-cancellated sculpture; the spiral ridges increase in number on the anterior whorls; suture 

 very deeply impressed, forming a sutural canal; body- whorl angulaled, base ornamented with fine 

 spiral and transverse lines; aperture subrectangular; outer lip thin, smooth; columella incrusted; 

 canal short. 



Dimensions. — Long. 13 mm.; lat. 5 mm.; body-whorl 6 mm.; aperture 3.5 mm.; defl. 

 23 degrees. 



This species is quite variable in sciilptiire, owiiiii to tlic varviiii;' luimber of 

 spiral ri(.lii;e.s on (lifTercnt indiviiliials. The specimen described was identified by 

 Dr. Da 11. 



Coiiunon in the lower San Pedro series at Deadman Island and San Pedro, 

 and in up{>er San Pedro series at Deadman Island, Crawfish George's, Los Cerritos, 

 and San Pedro. The specimen figured is from the upper San Pedro series at San 

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



Living. — Catalina Island to San Diego (Cooper). 



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



320. Bittium williamsoni, sp. iiov. 

 Platk VI, I'lu. 11. 



Shell small, elongate, turreted; whorls seven, angular, flat and sloping above, straight 

 below; upper .surface of whorl minutely cancellate with fine spiral and transverse ridges; lower sur- 

 face with two prominent spiral ridges and faint transverse ribs; suture deeply impressed, distinct; 

 aperture circular; base smooth; basal angle rounded slightly. 



Dimensions. — Long. 2.5 mm.; iat. i mm. 



This is the smallest of the IJitlininti found in llie San Pedro deposits, and is 

 distinguishable by its small size, prominently turbinated apex, and prominent can- 

 cellated sculpture. The specimen figured is the type, which was identified as a new 

 species by Dr. Dall, and which is now in the United States National Museum. 



Found in the upper San Pedro series of San Pedro. Also found in the 

 Pleistocene at Spanish Bight, near San Diego. 



Living.~{Vbi?) (Dall). 



Pleistocene. — San Pedro (Arnold). 



Subgenus Styliferina A. Adams. 



Diaphanous; conical turreted; whorls smooth, conve.x; apex mucronate; aperture subquad- 

 rate; inner lip straight. 



Bittium orthocJiila A. Ads. is a characteristic species. 



