ARNOLD — THE PALEONTOLOGY AND STRATIGRAPHY OF SAN PEDRO. 203 



Not uncommon in the upper San Pedro series at San Pedro, Deadman Island, 

 and Crawfish George's. Found also in the Pleistocene at Pacific Beach, San Diego, 

 and at the old irrigating ditch, Ventura. 



Living. — Monterey to San Diego (Cooper): Cerros Island (Dall). 



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

 Ventura (Arnold). 



Pliocene. — Santa Rosa; San Fernando (Cooper): San Diego well (Dall). 



169. Pleurotoma (Dolichotoma) cooperi, sp. nov. 



Plate VII, Fig. 3. 



Shell large, fusiform; spire elevated, same length as aperture; whorls seven, prominently 

 angulated near middle; upper portion decidedly concave, lower portion slightly convex; first five 

 whorls slightly nodose on angle, rest of whorls smooth on angle, except for roughness caused by in- 

 cremental lines; surface ornamented with revolving spiral ridges, most prominent on the lower portion 

 of whorls, and with prominent incremental lines, which, following the outline of the lip, are convexly 

 angulated posteriorly on the upper portion of the whorl and concavely angulated on the lower 

 portion; on the upper whorls the nearly equal prominence of the two systems of sculpture give the 

 shell a cancellated appearance; aperture long, narrow, with sides nearly parallel; outer lip thin, 

 arcuate anteriorly below sinus; inner lip smooth, incrusted; posterior sinus shallow, broad; canal 

 short, nearly as wide as aperture. 



Dimensions. — Long. 65 mm.; lat. 24 mm. ; body- whorl 42.5 mm.; aperture, including canal, 

 33 mm.; defl. 39 degrees. 



Distinguishable by the decided convexity of the upper portion of the whorl, 

 smooth angle and cancellated appearance of upper whoi'ls. 



Rare in upper San Pedro series of San Pedro; one specimen found. The 

 specimen figured is the type, which is from the upper San Pedro series at San Pedro, 

 and is now in the United States National Museum. 



Pleistocene. — San Pedro (Arnold). 



170. Pleurotoma (Dolichotoma) tryoniana Gabb. 



Pleurotoma ( Siircula) tryo7iiana Gabb, Pal. Cal., Vol. II, p. 6, PI. I, fig. 9, 1869. 

 Sicrcula t>yoyiiana Gabb, Cooper, 7th Ann. Rept. Cal. St. Min., 1888, p. 266. 



Shell resembles P. carpenteriana in shape; whorls eight, convex anterior to middle, with 

 row of nodes on angle; upper portion of whorls concave; surface ornamented with revolving ridges, 

 rather coarser on lower portion of whorl; suture impressed; aperture elongate, narrow, widest in 

 middle; outer lip thin, bulging below the wide, shallow sinus; inner lip smooth; canal short, broad. 



Dimejisiojis. — Long. 75 mm.; lat. 28 mm.; body-whorl 52 mm.; aperture, including canal, 

 40 mm.; defl. 33 degrees. 



Distinguishable by nodose, convex, angular whorls. 



Rare in upper San Pedro series of San Pedro. Mrs. Oldroyd has several 

 specimens of this species, which have been hauled up alive in the fishermen's nets at 

 San Pedro. 



Living. — San Diego (Cooper): San Pedro (Oldroyd). 



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



