no. 1617. NEW CRETACEOUS AND TERTIARY FOSSILS—ARNOLD. 8388 
left only shghtly convex; shell material somewhat nacreous, this 
character persisting in the type of the species; beaks small, bent only 
shghtly toward the posterior extremity ; anterior dorsal margin nearly 
parallel with base, rounds off gradually into anterior extremity ; pos- 
terior dorsal margin straight, forming an angle of about 140° with 
‘the anterior margin; posterior extremity somewhat angularly trun- 
cated. An internal rib extends from umbo to posterior ventral angle, 
this rib being reflected as a groove in that portion of the type speci- 
men which is preserved as a cast. A peculiar substratum of the shell 
is rather minutely radially striated, and this radiation is exaggerated 
by erosion on the type. Surface sculptured by numerous unequal 
but faint concentric undulations and fine incremental lines. Hinge 
similar to P. argentaria Conrad. 
Dimensions.—Length, 40 mm.; anterior extremity to beak, 25 mm.; 
latitude, 24 mm.; diameter, right valve, 7 mm.; left valve, 5 mm. 
Notes.—This species 1s closely allied to P. argentaria Conrad, from 
the recent fauna of California, and is probably the latter’s precursor. 
It is narrower and much more produced posteriorly, has the umbo 
less prominently bent toward the rear, and apparently has the radial 
striations in the substratum of the shell better developed than does 
P. argentaria. 
Named for the Santa Cruz quadrangle. 
Type.—tL. 5. J. U., No. 1074. 
-Horizon—Probable equivalent of Merriam’s “ Contra Costa Mio- 
cene,” basal upper Miocene. 
Localities —Santa Cruz quadrangle, Santa Clara County, locality 
No. 42, in soft sandstone on hill on the east side of Madera Creek, 
24 miles southwest of Mayfield. (R. Arnold, J. C. Branner.) 
GASTEROPODA. 
Genuse OSS eiannanrcke 
Subgenus PRISCOFUSUS Conrad. 
FUSUS (PRISCOFUSUS?) STANFORDENSIS, new species. 
Plate XXXYV, fig. 7. 
Description. shell attaining a length of 45 mm., rather broadly 
fusiform; apex acute; whorls 5 or more, regularly and prominently 
convex; upper whorls obsoletely spirally striate; sutural riblet at the 
upper margin of the whorl well developed; body whorl plump, 
faintly angulated in middle, spirally sculptured by numerous (8 or 9 
above angle) revolving major ribs, between each pair of which is a 
lesser rib; about 16 or 18 very faint varices cross the whorl and rise 
to faint nodes on the angle; surface sculptured also by fine incre- 
