216 CALIFORNIA ACADEMY OF SCIENCES. 



other in middle of lower portion of whorl; incremental lines visible; suture impressed, distinct; 

 aperture subovate, oblique; outer lip thin, slightly arcuate anteriorly; inner lip smooth; posterior 

 sinus broad, very shallow; anterior sinus short; columella short, distinct. 



Dimensions. — Long. 12 mm.; lat. 5.5 mm.; body-whorl 7 mm.; aperture 5 mm.; defl. 

 38 degrees. 



Distinguishable from others of the same family by the two strong, revolving 

 ridges. Named in honor of A. M. Strong. Specimens pronounced new species by 

 Dr. Dall. 



Rare in the lower San Pedro series of San Pedro and Deadraan Island; found 

 also in the Pliocene of Deadman Island, and in the upper San Pedro series at Craw- 

 fish George's. The specimen figured is the type, which is from the lower San Pedro 

 series at Deadman Island, and is now in the United States National Museum. 



Pleistocene. — San Pedro (Arnold). 



Pliocene. — Santa Monica; San Pedro (Arnold). 



Subgenus Spirotropsis Sars. 



Shell elongate, turreted, spire produced; the obtuse apex mammilliform; whorls numerous, 

 carinated in the middle; aperture narrow, oblique, with a short canal; sinus deep; remote from 

 suture. 



Plmrotoma carinatn Phil, is a characteristic species. 



194. Pleurotoma (Spirotropsis) smithi, sp. nov. 



Platk VI, Fig. 13. 



Shell elongate, turreted, slender; spire elevated; apex obtuse, mammilliform; whorls ten, 

 convex, with a slight tendency toward angulation on the lower third of the whorl, and abruptly 

 terminated at the posterior margin; suture very deeply impressed, distinct; sculpture consists simply 

 of oblique, incremental lines, which are quite deeply angulated convexly, posteriorly just a little above 

 the middle of the whorl; aperture narrow, oblique; outer lip thin, arcuate anteriorly; inner lip smooth 

 and incrusted; posterior sinus deep and remote from suture; canal narrow, slightly recurved, over 

 one-third of the aperture. 



Dimensio7is. — Long. 35 mm.; lat. 11 mm.; body-whorl 8.5 mm.; aperture 13 mm.; defl. 

 19 degrees. 



A long, slender species, slightly resembling the sinistral P. perversa in general 

 outline, but easily distinguishable from that species and also from all the other 

 members of this family. Some of the shells are a little more depressed than the tyjie. 

 Specimens identified by Dr. Dall as being a new species. 



Not uncommon in tiie lower San Pedro series and Pliocene of Deadman 

 Island. The specimen figured is the type, which is from the Pliocene of Deadman 

 Island, and is now in the United States National Museum. 



Living. — (Locality not mentioned) (Dall). 



Pleistocene. — San Pedro (Arnold). 



Pliocene. — San Pedro (Arnold). 



