362 PROCEEDINGS OF THE NATIONAL MUSEUM. VOL. XXXIV. 
Named in honor of the late Dr. P. P. Carpenter, widely known in 
relation to his work on West American conchology, who named two 
west coast species of this genus. 
Type.—Slightly imperfect specimen, Cat. No. 165483, U.S.N.M. 
Horizon.—Martinez (?) formation, lower Eocene. 
Localities —Santa Cruz quadrangle, San Mateo County, locality 
No. 25, ridge between headwaters of San Lorenzo River and Pesca- 
dero Creek. (H. S. Gay, R. Arnold.) 
Genus PATELLA Linnezeus. 
PATELLA MATEOENSIS, new species. 
Plate XXXII, fig. 7. 
Description —Shell averaging about 7.5 mm. in longitude, conical, 
with subelliptical base, very slightly narrowed in front; beak acute, 
sheghtly anterior; profile from beak to both extremities shehtly convex 
upward; margin wavy to serrate. Surface sculptured by numerous 
fine, more or less irregular lines of growth and about 22 narrow, 
ridge-like radiating ribs separated by wide flat-bottomed interspaces 
in which are often intercalated one or more minor riblets. 
Dimensions.—Length, 7.5 mm.; latitude, 5.4 mm.; altitude, 2 mm. 
Notes——This species is similar in general outline to Patella, new 
species, b, but a series of over twenty specimens of the two show no 
intermediate forms. P.mateoensis is distinguished from Patella, new 
species, b, by its fewer, narrower ribs, which are simple instead of 
dichotomous, and between which are wider interspaces each usually 
containing one or two minor riblets. Named for San Mateo County, 
in which the type locality is situated. 
Type.—Cat. No. 165437, U.S.N.M. 
Horizon.—Martinez (?) formation, lower Eocene. 
Localities —Santa Cruz quadrangle, San Mateo County, locality 
No. 25, ridge between San Lorenzo River and Pescadero Creek. 
(Hi. S. Gay, R. Arnold.) 
Genus FISSURELLA Bruguiere. 
FISSURELLA PERRINI, new species. 
Plate XXXII, fig. 4. 
Description.—Shell averaging about 16 mm. in longitude, conical, 
flaring slightly toward bottom; base oblong, narrowed in front; 
margin notched; apical hole oblong, with plane of margin tilted 
slightly forward, situated a little more than one-third the length of 
the shell from the anterior extremity. Surface sculptured by 
numerous (38 in type) quite regular, rounded, slightly elevated radi- 
ating ribs, separated by flat-bottomed interspaces usually slightly 
wider than the ribs, and also by numerous sharp, imbricating, wavy, 
