ARNOLD — THE PALEONTOLOGY AND STHATIGRAPHY OF SAN PEDRO. 223 



Found in the lower San Pedro series at San Pedro, and in the up[)er San 

 Pedro series at Deadman Island, San Pedro and Crawfish George's. 



Xm?i^.— Farallon Islands to San Diego; South America (Cooper). 



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

 Pedro (Arnold). 



Pliocene. — San Pedro (Arnold). 

 f 



Genus Mitromorpha A. Adams. 



Shell small, elongately fusiform; whorls flattened, with revolving lirae, and sometimes longi- 

 tudinally plicate; aperture narrow; columella straight, slightly transversely Urate; lip acute, smooth 

 within, scarcely sinuated posteriorly. 



Mitromovplia gracilis Carpenter is a characteristic species. 



205. Mitromorpha filosa Carpenter. 



? Daplmella filosa CpR., Brit. Assn. Rept., 1863, p. 658. 



Mitro77iorpha filosa CpR.,* Keep, West Coast vShells, p. 55, 1S92. Williamson, Proc. U. S. 

 Nat. Mus., Vol. XV, 1892, p. 200, PI. XIX, fig. i. 



Shell small, mitre-shaped; apex rounded; whorls six, flat, ornamented with several sharp, 

 raised, revolving lines; suture impressed, distinct; aperture long, narrow, oblique; outer lip denticu- 

 late interiorly; inner lip smooth; columella spirally lined externally. 



Ditnensions. — Long. 8 mm.; lat. 3.6 mm.; body-whorl 6 mm.; aperture 5 mm.; defl. 

 55 degrees. 



A shell from the Pleistocene shows transverse ridges on first four whorls, but 

 these become obsolete below this. This transversely ridged specimen is intermediate 

 between the typical M. filosa and M. intermedia. M. aspera is jirobably the type of 

 the precursor of the three West Coast species mentioned, then in phylogenetic order 

 would come M. intermedia, specimens like the ridged variety of J\I. filosa, and lastly 

 typical M. filosa. The cancellate upper whorls of all the species except M. filosa 

 show j\J. aspera to be the precursory form. 



One specimen in lower San Pedro series of San Pedro. 



Living. — Santa Barbara (Carpenter): San Pedro (Simpson). 

 Pleistocene.- — San Pedro (Arnold). 



206. Mitromorpha intermedia, sp. nov. 



Plate IV, Fig. 10. 



Shell small, mitre-shaped; apex rounded; whorls six; slightly convex; whorls ornamented 

 with about four equidistant, sharp, raised spiral lines, and numerous rounded, transverse ridges which 

 are most prominent on angle of whorl; ridges are obsolete, or nearly so, on body-whorl; suture quite 

 deeply impressed; aperture long, narrow, oblique; outer lip slightly arcuate anteriorly, smooth 

 interiorly; inner lip smooth; columella spirally lined externally. 



Dimcnsio7is. — Long. 9.5 mm.; lat. 3.9 mm.; body-whorl 6.5 mm.; aperture 4.5 mm.; defl. 

 36 degrees. 



