PLATE XXVII. 
Miocene Pelecypoda and Gasteropoda. 
Fig. 1. Peden (. Lyropecten) bowersi Arnold. Univ. California. Type. Right valve; 
altitude 150 mm.; about two-thirds natural size. Lower Miocene, Santa 
Inez Mountains, Santa Barbara County. Also abundant at same horizon 
in Santa Monica Mountains and elsewhere. Left valve of this species 
more convex than right; otherwise very similar. 
Fig. 2. Ostrea titan Conrad. U.S.N.M. 164987. Side view of both valves; altitude 
of large valve 131 mm.; two-thirds natural size. Lower Miocene, 3 miles 
south of Calabasas, Los Angeles County. This species is found in both 
the upper and lower Miocene, and often grows to a length of 20 inches (500 
mm.) (See PI. XXXII, fig. 2.) 
Fig. 3. Purpura edmondi Arnold. U.S.N.M. 164983. Type. Aperture view; alti¬ 
tude 19 nun.; about 1J times natural size. Lower Miocene, 3 miles 
south of Calabasas, Los Angeles County. 
Fig. 3a. Reverse view of same specimen as fig. 3; same enlargement. 
Fig. 4. Chlorostoma ( Omphalius) dalli Arnold. U.S.N.M. 164984. Type. Aperture 
view; latitude 12.5 mm.; 1J times natural size. Lower Miocene, 3 miles 
south of Calabasas, Los Angeles County. A common species in this 
horizon. 
Fig. 4a. Top view of same specimen as fig. 4. 
Fig. 46. Base view of same specimen as fig. 4. 
Fig. 5. Chlorostoma ( Omphalius) dalli var. inornatus Arnold. U.S.N.M. 164986. 
Type. Top view; latitude 13.5 mm.; 1J times natural size. Same 
locality as fig. 4. 
Fig. 6. Chlorostoma ( Omphalius) dalli var. subnodosus Arnold. U.S.N.M. 164985. 
Type. Top view; latitude 13 mm.; 1J times natural size. Same locality 
as Fig. 4. 
Fig. 6a. Base view of same specimen as fig. 6. 
Fig. 7. Cerithium topangensis Arnold. U.S.N.M. 164976. Type. Aperture view of 
imperfect specimen; longitude 23 mm.; times natural size. Lower 
Miocene, 3 miles south of Calabasas, at head of Topanga Canyon, Los 
Angeles County. A common species at the type locality. 
Fig. 8. Cerithium topangensis Arnold. U.S.N.M. 164976. Cotype. Aperture view 
of imperfect specimen; longitude 13 mm.; IJ times natural size. Same 
locality as fig. 7. 
Fig. 9. Cancellaria cf. condoni Anderson. U.S.N.M. 164981. Back view of imperfect 
specimen; altitude 21 mm.; 1J times natural size. Lower Miocene, 3 
miles south of Calabasas, Los Angeles County. This species appears to 
range from the San Joaquin Valley to the Santa Monica Mountains in the 
lower Miocene. 
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