PLATE XXVIII. 
Miocene Pelecypoda and Gasteropoda. 
Fig. 1. Pecten ( Lyropecten ) magnolia Conrad. Univ. California. Imperfect right 
valve; altitude 14.5 mm.; about two-thirds natural size. Lower Miocene, 
Yaqueros formation, Ojai Valley, Ventura County. Characteristic of the 
lower Miocene throughout central and southern California. The left valve 
has narrow, more rounded ribs. 
Fig. 2. Pecten (Lyropecten) estrellanus Conrad. U.S.N.M. 164851. Left valve; alti¬ 
tude 97 mm.; about two-thirds natural size. Upper Miocene, Wildhorse 
Canyon, Monterey County. This species is usually abundant in both the 
lower and upper Miocene faunas of central and portions of southern Cali¬ 
fornia. Ribs of right valve broader and anterior ear notched; otherwise 
similar to left. 
Fig. 3. Drillia sp. U.S.N.M. 164977. Type. Back view; longitude 13.5 nun.; about 
1J times natural size. Lower Miocene, head of Topanga Canyon, 3 miles 
south of Calabasas, Los Angeles County. 
Fig. 4. Macron merriami Arnold. U.S.N.M. 164982. Type. Aperture view; longi¬ 
tude 23 mm.; about 1J times natural size. Lower Miocene, same locality 
as fig. 3. This species appears to range over central and southern Cali¬ 
fornia in the lower Miocene. 
Fig. 4a. Back view of same specimen as fig. 4. 
Fig. 5. Sigaretus perrini Arnold. U.S.N.M. 164979. Type. Aperture view of par¬ 
tially decorticated and imperfect specimen; altitude 18.5 mm.; about 1^ 
times natural size. Lower Miocene, same locality as fig. 3. 
Fig. 6. Turbo topangensis Arnold. U.S.N.M. 164980. Type. Aperture view; alti¬ 
tude 18.5 mm.; about 1J times natural size. Lower Miocene, same 
locality as fig. 3. 
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