ARNOLD] FOSSIL MOLLUSKS FROM CALIFORNIA 427 



calaries) between ; in others the ribs are irregularly disposed, al- 

 though there is a tendency for the alternate ones to be larger and 

 sometimes dichotomous. Ears radially striate in addition to incre- 

 mental imbricating sculpture ; anterior ear of right valve with deep 

 byssal notch and well isolated byssal area. 



Dimensions. — Latitude (restored) 75 mm. 



Notes. — The imperfect fragments which furnish the characters 

 described above represent a species apparently allied to P. per run 

 Arnold, although it is smaller and has more numerous and less imbri- 

 cate ribs than the latter. P. ynesiana is the only species of this group 

 found in the Eocene. It has been recognized in the Tejon formation 

 throughout the whole length of the Santa Ynez Range, and as far 

 east as the Ojai Valley, Ventura County. 



Type. — Cat. No. 165,313, U. S. N. M. Paratype, same number. 



Locality. — San Julian ranch, 10 miles southeast of Lompoc, Santa 

 Barbara County, California ; locality No. 4507. 



Horizon. — Tejon formation, Eocene. 



New Lower Miocene (Vaoueros Formation) Species 



PURPURA VAQUEROSENSIS, new species 



PI. LII, figs, ra and lb 



Description. — Shell averaging about 100 millimeters in altitude, 

 very broadly spindle-shaped, spire elevated, conical ; apex subacute. 

 Whorls 4 or 5, sharply angulated anteriorly immediately adjacent to 

 suture, portion posterior to angle flat except for a slight concavity 

 just in front of suture caused by bending back of posterior margin 

 where it appresses against antecedent whorl. Suture appressed, 

 wavy, distinct, sometimes encroaching on angle of posterior whorl. 

 Sculpture of the penultimate and preceding whorls confined to fine 

 backward-sloping incremental lines and sometimes a faint suggestion 

 of nodes on the angle ; body whorl biangulate, the posterior angle 

 being the more prominent owing to a row of prominent nodes ( 10 in 

 type), some of which are quite regular, some more or less spirally 

 elongate, and others approaching the importance of spines, anterior 

 angle consisting of a rounded spiral ridge and below this four other 

 similar revolving ridges, separated by impressed lines ; area between 

 the two angles flat or slightly convex and carrying four obsolete 

 spiral ridges ; whole surface of whorl crossed by sharp imbricating 

 lamellae, which slope backward on posterior portion of whorl and rise 

 to the importance of imbricating spines on the second and fourth 

 ridges in front of anterior angle and occasionally on the other ridges. 



