122 TERTIARY AND QUATERNARY PECTENS l)F CALIFORNIA. 



Dhnenmonf^. — Alt. CA uiiii.: long, n?, niiii.: hinoe line 11> iimi.: diameter, 

 right valve 10 mm.; left valve 13 mm. 



Tlli.s variety is similar to the typical /'. ivattsi, except that it Is somewhat less 

 convex and less constricted, and, as a consequence, has no prominent nodes on the 

 ribs of the left valve. Both the typical P. vxxttsi and its varietj' rnorani are allied to 

 P. hiimUni, but are much taller and have relatively much shorter ears and narrower 

 ribs. The degree of convexity is approximately the same in P. hamUiii and P. 

 HHittsi var. iiiorani. 



P\ wattsi var. moranl is known .so far onl}* from beds exposed on Mi'. T. H. 

 Moran's place, Priest Valley, Monte re j' County, where it is associated with Area 

 iqf.) trili'iieata Conrad, Ostrea {'yf.) horidu Carpenter, Ec]i>narachniii» {cf.) cvcen- 

 tricus Eschscholtz, and ScnfeJJa /(nj'hanJi'tii Merriam^. This fauna probably indi- 

 cates a lower Pliocene horizon. 



The type is an almost perfect left valve (U. S. N. M. No. 16-±y2i>) and, together 

 with the other figured specimens, comes from Mr. Moran's place in Priest Valley, 

 Monterej' Count}'. 



KAXGE. 



Pliocene (lower). T. H. Moran's place, SW. i sec. 11, T. 20 S.. R. 12 E., Mount 

 Diablo meridian. Priest Valley. Monterey County (Hamlin and Arnold). 



Pectex (Lyropecten) ashleyi n. sp. 



PI. XLVII, figs. 1 and la; PI. XLVIII, fig. 1 

 189.'i. Pecten eMrellanm Awliley (not of Conrad, 1S.57), Proe. Cal. Acad. Sci., ser. 2, vol. 5, 1895, p. 3.38. 



I)e>i<'riptton. — Adult shell averaging about 150 millimeters in altitude, nuich 

 longer than high, suljequivahc, convex, inecjuilateral, the posterior portion of the 

 disk being obliquely produced; sides concave above. Right valve with about IS or 

 19 prominent, rather squarish, tiat-toppcd (convex-topped near umbo) ribs which 

 are more or less prominently sculptured l)y numerous thread-like, somewhat imbri- 

 cated, radial ridges; inter.spaces narrower than ribs, channeled and ornamented by 

 an intercalary riblet and, in the later stages of growth, by several imbricated radial 

 lines; hinge line about one-half length of disk; anterior ear sonu'what produced, 

 prominently notched and sculptured by numerous imbricating incremental lines 

 and several more or le.ss prominent luiequal radials: posterior ear slightly shorter 

 than anterior, and similarly sculptured except with more, Imt less conspicuous, 

 radials. Left valve slighth' more convex than right and similar to it except that 

 the ribs are slightly narrower and more convex, and the interspaces are corre- 

 spondingly wider and generally have the bottom entirely sculptured with subequal 

 radial lines, with the prominent intercalary lacking; ears subequal. rectangidarly 

 truncated and sculptui-ed in a similar manner to the posterior ear of the right 

 valve. 



Dlme7isionf>. — Alt. 152 mm.; long. 175 mm.: hinge line S5 mm.; diameter 

 65 mm.; apical angle 110'. 



This raagniticent species is characterized and is distinguishable from allied 

 forms }iy its great relative length and numerous ribs {P. crassicardo, a nearly 



