PLATE XXXIII. 
Miocene Pelecypoda and Gasteropoda. 
(All figures natural size.) 
Fig. 1 . Pecten ( Chlamys) sespeensis Arnold. California State Mining Bureau. Cotype 
Portion of mold of interior of right valve; altitude 50 mm. Lower Mio¬ 
cene, Yaqueros formation, Sespe Canyon, Ventura County. A common 
species at the type locality; also found elsewhere in central and southern 
California in the lower Miocene. 
Fig. la. Mold of interior of left valve of same specimen as fig. 1. 
Fig. 2. Pecten (Chlamys) sesjieensis Arnold. California State Mining Bureau. Plasto- 
type. Cast of exterior of slightly imperfect left valve (young); altitude. 
18 mm. Same locality as fig. 1. 
Fig. 3. Pecten ( Lyropecten) vaughani Arnold. Collection of Delos Arnold. Type. 
Right valve; altitude 37 mm. Lower Miocene, supposed equivalent of 
Vaqueros formation, Ojai Valley, Ventura County. 
Fig. 3a. Same specimen as fig. 3. Left valve. 
Fig. 4. Dosinia ponderosa Gray. U.S.N.M. 164988. Imperfect right valve; altitude 
80 mm. Lower Miocene, 3 miles south of Calabasas, Los Angeles County. 
A common species from the lower Miocene to the Recent southern fauna 
of the west coast. 
Ftg. 5. Pleurotoma ( Dolichotoma) keepi Arnold. U.S.N.M. 164993. Type. Back 
view of imperfect specimen. Same locality as fig. 4. Found also in this 
horizon at several localities in southern San Joaquin Valley. 
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