366 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL XXXIV. 
Miocene series west of Gettysburg and west of Port Crescent, Clallam 
County, and in Kitsap County, opposite Seattle, Washington (R. 
Arznold) ; Oligocene, Porter, Washington (R. Arnold). 
Genus CARDIUM (Linnzeus) Lamarck. 
CARDIUM COOPERI Gabb, var. LORENZANUM, new variety. 
Plate XXXIII, fig. 6. 
Description.—Shell attaining a length of only about 14 mm.; some- 
what longer than high; end view of both valves together has a cor- 
date appearance; outline of a single valve subcircular; shell very 
convex, thin; umbo small, prominent, turned shghtly forward, pro- 
jecting beyond dorsal margin; dorsal margin straight for short dis- 
tance under umbo, bends off shghtly more angularly posteriorly than 
it does anteriorly ; extremities broad and regularly rounded, as is also 
the base; surface sculptured by fine incremental lines and by numer- 
ous fine radiating lines, those over the posterior end being larger and 
more prominent than those on the remainder of the shell, and dis- 
tinctly separated from the latter by a faint angle in the surface of the 
shell extending from umbo to posterior ventral margin. Margin 
minutely crenulate. Lunule faint or lacking. 
Dimensions.—Length, 14 mm.; altitude, 12.5 mm.; diameter of 
single valve, 4.5 mm. 
Notes.—Gabb, in the original description * of C. coopert, writes that 
no carina or angle separates the two differently sculptured portions 
of the shell. Specimens of C. coopert from the Eocene of Rose Can- 
yon, north of San Diego, show a faint angle at this point. (. coop- 
eri Gabb, var. lorenzanum, new variety, apparently differs from the 
typical Kocene form in size only, the latter often attaining a length 
of nearly 40 mm., although in the type of the new variety the lunule 
is lacking. Other specimens from the same horizon as the latter 
show a faint lunule. The small variety is apparently confined to the 
Oligocene, while the typical form is characteristic of the Eocene. 
Type.—Slightly imperfect right valve, Cat. No. 165444, U.S.N.M. 
(Locality No. 4063, Porter, Washington.) 
fTorizon.—San Lorenzo formation, Oligocene. 
Localities —Santa Cruz quadrangle, Santa Cruz County, locality 
No. 101, on San Lorenzo River, 32 miles north of Boulder Creek; 
locality No. 103, on Kings Creek, one-half mile above confluence with 
San Lorenzo River; locality No. 106, on Twobar Creek, seven-eighths 
mile above its confluence with San Lorenzo River; locality No. 107, 
on small ravine off Boulder Creek, 24 miles north of Kagle Rock; 
locality No. 108, beside road on ridge between headwaters of South 
Fork of Waddell Creek, and Boulder Creek, 1 mile north of Eagle 
OP, CBU, Il, fe Is 
