54 TKRTIARY AND QirATERNAKY PECTKNS OF CALIFORNIA. 



(iabb .states thiit the type of /'. inti'rradiatm i.s from the -'buti'-colored shale 

 east of New Idria, at or near the summit of the Tejoii tiroiip" [Eocene], where he 

 found it very ahundant. Two specimens from the collection of the University of 

 California, which were collected by Mr. H. W. Turner at New Idria. are in a hard, 

 darU -colored shale. 



A Pri-imi allied to /*. Jntcrriidt^itus. accompanied by the followinjj- note, was 

 sent to the writer by Dr. J. C. Merriam, of Berkeley: "Road cutting below 

 Professor Richer's house at mouth of Strawberiy Canyon, Berkeley. Cutting now 

 walled up. A. C. L. Cretaceous shale." This species, which is represented by an 

 intei-nal cast, is 12 millimeters in altitude, 10 millimeters in longitude, and has a hing(> 

 line ?..5 millimeters in length. It has In prominent rounded internal ribs extending 

 from the umbo nearly to the periphery, and in several of the broad interspaces a 

 rounded intercalary, which tiegins at a distance of about 7.5 unllimeters from the 

 umbo ^nd extends nearly to the periphery. The anterior ear of the shell (which is 

 a right valve) is slightly longer than the posterior, arcuate in front, and has but a 

 faint suggestion of a byssal notch. 



The figures of /'. hi/c/'radiatiw, which are natural size, are copied from tli(> 

 originals of the type in Pal. Cal., vol. 2, pi. HH. Kgs. DS. HSa. 



Eocene (upper Tejon). New Idria, San Benito County (Gal)b: Turner). 



(iLIGOCENE PECTEXS. 



I Those known tirat to appear in the Oligocent- I'nrraatiitns.] 



Pectkn (Pecten) sanct^cruzensi.s n. sp. 



V\. TIT. litrs. 12 and l:!. 

 190:;. I'lilfH (Pecleii) Imihdirnnin AriioM, MS. 



Dr-i('r/j)f,/'o/i. — Shell averaging about 60 millimeters in altitude, slightly longer 

 than high, plano-convex, ecjiulateral, rath(>r thin; base regularly rounded; sides 

 only slightly concave tibove; margins smooth. Right valve quite convex and 

 oi-namented with about 12 prominent, perpendicular-sided, slightly convex-topped 

 ribs, separated by tlat-bottomed. channeled interspaces about eipial in width to the 

 ribs; surface sculptured by small, almost imperceptible, obsolete, radiating striations 

 and numerous tine sharp concentric lines; hinge line considerably longer than one 

 half length of disk; ears sul)equal; anterior with shallow by.ssal notch and tine, 

 sharp concentric lines; posterior similarly sculptured, but rectangularly truncated. 

 Left valve flat, with slight concavity near umbo; lateral areas rather prominent; 

 ribs squarish, with slightly convex tops narrower than those of the right valve 

 and with proportionally wider interpaces; ears sul)equal, rectangularly truncated, 

 and with surface sculptured by numerous tine, sharp incremental lines. 



Oiiiii'iixidns. — Alt. 52 mm.: long. 55 mm.; hinge line 32 mm.; diameter about 

 \'.\ nun.: unbonal angle lio . 



This species is allied to P. hellux and may be its precursor, as it is very 

 similar to the latter in most respects. P. sancffecimzenxis may be distinguished 



