MIOCENE PECTENS. 63 



Pecten (Patinopecten) oweni n. sp. 



PI. VIII, tigs. 1, 1", and \h. 



1,S8S. Pectcii pahloensif: Cooper (not Conrad), Seventh .\nn. Rept. Cal. St. .\Iin., 1.SH8, j). 258 ("Foxins, 



Santa Barbara County" record, only). 

 1898. Pecten sp., Dall, Trans. Wagner Free Inst. Sci., vol. 3, pt. 4, 1898, p. 705, line 27. 



Dmcript'iini. — Shell averaging about 85 niillinietcis in altitude, slig'htly longer 

 than high, inequivalve, equilateral, and with more or les^; .serrate margins; ha.se 

 regularly rounded; sides somewhat concave above. Right valve much more con- 

 vex than the left, with 15 or !•> subequal. strong, elevated, squarish ribs, which 

 become more or less deeply medially sulcated after about \y\ or 50 millimeters in 

 length; interspaces about as wide as ribs, channeled and ornamented with more or 

 less prominent rounded intercalary rihlets; whole sui'face of disk sculptured by 

 fine lines of growth; hinge line considerably longer than length of disk; anterior 

 ear slightly longer than posterior, obsoletely radially ribbed, and with sharp incre- 

 mental sculpture; byssal notch quite prominent and equal in width to about one- 

 third width of ear; posterior ear rectangularly truncated and with prominent 

 incremental, but nearly obsolete, radial sculpture. Left valve less ventricose than 

 right: ribs quite high, narrow, and rounded: interspaces much wider than ribs. 

 with round bottoms, and each ornamented by a prominent rounded intercalary 

 rib; surface sculptured by numerous sharp, regular, concentric lines; ears slightly- 

 obliquely truncated and sculptured as those of right valve. Hinge as in P. 

 i-aiirinu.'i. 



Dimensionif. — Alt. 85 mm.; long. 90 nini.: hinge line 54 nmi.; diameter '24 mm. 



This species is quite closely allied to /'. Iwahi/i^ of which it is probably the 

 precursor. It may be distinguished from the latter by its smaller size, greater 

 convexity, fewer and stronger ribs, more prominent intercalarv riblets on the 

 right valve, and relatively much longer hinge line. 



1^. inoeni is found in a horizon which is probably low down in the Pliocene, 

 and also in deposits, such as those at Foxin's ranch, Santa Barbara County, from 

 which the type comes, that ma}' be upper ]\liocene. Specimens of this species 

 have been found in the lower part of the Purisima (Pliocene) formation north of 

 the mouth of Purisima creek. There appears to be more or less of a gradation 

 from P. oweni to P. healeyi as we go up in the Purisima formation. The rather 

 convex, 17 and 18 ribbed forms of P. healeyi, mentioned as occurring at Lobitas 

 and Purisima, .seem to furnish a more or less intimately connecting link between 

 the latter species and 1'. oioeni. 



The type of /'. ouie^il, which is figured,, is now in the collection of the 

 University of California. This specimen was labeled "P. pallotfiis/'s'' b}- Doctor 

 Cooper and furnished the erroneous record of P. jiahloensis from "'Foxins, Santa 

 Barbara County" (.see Cooper, 1888, p. 258). 



In the Pliocene beds of Temescal Canyon, near Santa Monica. Los Angeles 

 Count}', P. owenl is associated with P. stcarnsii^ P. estrdlanus var. catalmas, P. 

 cerroserisiii and other Pliocene species. 



