35 



1036 Pisidium ultramontanum Prime. 

 1704 Pisidium scutellatum 

 1168 Pisidium variabile Prime. 

 51 Pisidium virginicum 



997 Pilidium fulvum Muller. 



2150 Pitaria Newcombiana Gabb. 1865. 



2151 Pitaria unicolor Sby. 1835. 



2153 Pitaria vulnerata Brod. 1835. 



2154 Pitaria lupanaria Lesson. 1832. 



2155 Pitaria rosea Brod. & Sby. 1829. 



2156 P: (Lamelliconcha) concinna Sby. 1835. 



2157 P: circinata alternata Brod. 1835. 



998 Placiphorella latior Carpenter. 



999 Placiphorella imporcata Carpenter. 



1000 Placiphorella sinuata Carpenter. 



1001 Placiphorella velata Carpenter. 



331 Placunanomia macroschisma Desb. 



2294 Planaxis nigritella Forbes. 



2295 Variety — ? 



1002 Planorbis ammon Gould. 

 37 Planorbis bicarinatus 



1682 Planorbis callioglyptus 

 36 Planorbis campanulatus 



1004 Planorbis deflectus Say. 



1005 Planorbis exacutus Say. 38 

 3171 Planorbis Gracilentus Gould, 1855. 1006 



1007 Planorbis hornii Tryan. 



39 Planorbis Lentus 



1008 Planorbis opercularis Gould. 

 2131 Planorbis Liebmanni Dunker. 

 1994 Planorbis opercularis multilineatus 



1683 Planorbis opercularis oregonensis 



40 Planorbis parvus 



1217 Planorbis trivolvis Say. 



1680 Planorbis centervillensis Tryon. 



1710 Planorbis nautileus L. 



2329 Planorbis petenensis Morel. 



1012 Planorbis tumidus Pfeiffer. 



1658 Planorbis umbilicatellus Cockerell. 



1013 Planorbis vermicularis Gould. 



332 Platidia anomioides (Scaccbi) Costa var? 

 279 Platyodon cancellata Conr 



1014 Plectodon scaber Carpenter. 



1015 Pleurobranchus calif ornicus 



1372 Pleurotonia callicesta. Acapulco. 600 fms. 



1562 Pleurotonia Carpenteriana Gabb. 



2427 Pleurotonia (Antiplanes) Catalinae 

 1371 Pleurotonia circinata 



2430 Pleurotoma (Genota) Cooperi Arnold. Quaternary. 



1016 Pleurotoma hemphillii 



1017 Pleurotoma montereyensis 



1018 Pleurotonia luctuosa Hinds 



1366 Pleurotoma (Antiplanes) perversa Gabb. 



1368 Pleurotoma (Antiplanes) piona. Bering sea. 



2428 Pleurotoma (Genota) Riversiana 

 1370 Pleurotonia (Antiplanes) santarosana 

 2426 Pleurotoma (Genota) Stearnsiana 



1369 Pleurotoma (Antiplanes) thalaea 



2429 Pleurotoma (Genota) Tryoniana Gabb. Tertiary to recent. 



1019 Pleurotoma tuberculifera Gray. 



