ARNOLD — THE PALEONTOLOGY AND STKATIGEAPHY OF SAN PEDEO. 227 



rohustus is a degenerate form in so far as size and beauty go, for rugosus is truly a 

 magnificent shell, while the former is small and much less attractive. This species 

 has been identified as F. amhiistus, and is so labeled in the State Museum collection 

 at Berkeley. F. nmbusfus of Gould is a slenderer, longer pillared form from Central 

 America. 



Found only in the lower San Pedro series of Deadman Island. The shells in 

 this horizon are beautifully preserved, this form especially being nearly always found 

 in a perfect condition, and having a shell that in most cases is translucent. Rather 

 rare. The specimen figured is from the lower San Pedro series at Deadman Island, 

 and is now in the collection of Delos Arnold. 



Living.—Santa Barbara to San Diego (California State Museum). 



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



Genus Pisania Bivona. 



Shell oblong; spire prominent; whorls smooth or spirally striated; canal very short; outer 

 lip thickened and crenated. 



Pisania pusio Linn, is a characteristic species. 



211. Pisania fortis Carpenter. 



Pisania foriis Cpr., Ann. & Mag. Nat. Hist., 3rd Sen, Vol. XVII, 1866, p. 277. Cooper, 7th Ann. 

 Rept. Cal. St. Min.. 18S8, p. 260. 



Shell fusiform, short; spire elevated; apex subacute; whorls five or six, convex on upper 

 whorls to angular on body-whorls; eight wave-like ribs, most prominent on the angle of the whorl; 

 prominent sutural riblet on posterior margin of whorl; surface ornamented with three to five promi- 

 nent, squarish, rough, revolving ridges, between which are finer raised lines; suture wavy, appressed, 

 distinct; aperture pyriform; outer lip denticulated; umbilicus subperforate. 



Dimensio7is. — Long. 49 mm.; lat. 29 mm.; body-whorl 38 mm.; aperture 25 mm.; defl. 

 58 degrees. 



This species resembles some specimens of Purpura crispata, but is a lighter 

 shell, and the sculpture is entirely different. Originally described from a specimen 

 from the Pleistocene of Santa Barbara. It has never been found living. 



Rare in the upper San Pedro series of San Pedro and Deadman Island; two 

 specimens found. Found in the Pleistocene at Pacific Beach, San Diego. 



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



Family LVIII. BUCCINID^. 



Genus Chrysodomus Sivainson. 



Shell fusiform, ventricose; spire elevated; whorls rounded; covered with a horny epidermis; 

 apex papillary; aperture oval; canal short; inner lip simple, smooth. 



Chrysodomus antiqua Linn, is a characteristic species. 



