428 SMITHSONIAN MISCELLANEOUS COLLECTIONS [VOL. 50 



Columella twisted and recurved, the lower portion overlapping a 

 narrow canal ; columella strongly sculptured by incremental lines. 

 Aperture ovate ; outer lip simple. 



Dimensions. — Altitude, ioo mm. ; latitude, 68 mm. ; altitude of 

 body whorl, 92 mm. ; longitude of aperture, including canal, 80 mm. 



Notes. — In all of the specimens of this species examined the 

 aperture and the greater part of the columella are unfortunately 

 concealed. It appears, however, from external characteristics to be- 

 long to the genus Purpura, and to that group of the genus repre- 

 sented by P. tricercalis Blainville and P. triangularis Blainville, al- 

 though P. vaqucrosensis is very much larger than either of the latter. 

 This magnificent species is known in the lower Miocene from Mon- 

 terey County south to Santa Barbara County, and is, so far as the 

 writer is aware, confined to this one horizon of the Miocene. It is 

 one of the prominent members of the very characteristic fauna of 

 which Pectcn magnolia Conrad, Turritella ineziana Conrad, and 

 Cardiuni, new species near quadrigenariwn, are a part. Named for 

 the Vaqueros formation (lower Miocene), of which it is believed to 

 be characteristic. 



Type. — Collection of Delos Arnold, Pasadena, California. 



Locality. — -Lynch Mountain, Monterey County, California. 



Horizon. — Vaqueros formation, lower Miocene. 



PECTEN (PECTEN) VANVLECKI, new species 



PI. Lill, figs. 1 and 2 



Description. — -Shell averaging about 70 millimeters in altitude, 

 length and height about equal, outline circular ; both valves convex, 

 the right slightly more so than the left, equilateral, thin ; base regu- 

 larly rounded ; sides only very slightly concave above ; margins 

 smooth. Right valve somewhat convex, the region of greatest con- 

 vexity being just below the beak; surface ornamented with 13 or 14 

 rather prominent ribs, these being quite rounded in the younger 

 stages of growth, but gradually becoming flatter and lower toward 

 the periphery ; interspaces rounded near umbos, but shallower and 

 flatter below ; equal, fine, sharp, raised incremental lines, separated 

 by interspaces as wide as the lines, cover the surface of the disk and 

 ears ; hinge line longer than half length of disk ; ears subequal, 

 anterior with shallow byssal notch ; posterior rectangularly trun- 

 cated. Left valve slightly less convex than right, flat to concave 

 immediately below umbo; ribs regularly rounded throughout entire 

 length, becoming flatter and sometimes almost obsolete toward the 



