Vol. IX) SMITH— CLIMATIC RELATIONS 127 



California, but is still living in the Indian Ocean region. 

 Lyropecten is a Miocene group in middle California, survives 

 into lower Pliocene in southern California, and is still living 

 in Lower California. Miopleionia is an Oligocene genus in 

 the Puget Sound region, but in middle California is character- 

 istic of lower Pliocene. 



The writer has prepared a table of diagnostic forms used 

 as criteria in determining the age of West Coast formations. 

 This table is given below. But since an important genus or 

 species may be common in one geographic region and lacking 

 in another, or may be characteristic of a certain horizon in 

 one and of a different horizon in another region, still another 

 table has been prepared, showing the climatic as well as geo- 

 logic range of the important forms. This brings out espe- 

 cially well the differences in geologic range of the same species 

 in different latitudes. In this table the occurrence of a form 

 is registered with ( + ), and the absence of a form from a 

 horizon in one province is registered with (0). 



Diagnostic Forms in West Coast Neozoic Faunas. 



EOCENE. 



Many extinct genera: Strepsidura, Ficopsis, Perissolax; 

 many genera now confined to the tropics : Avicula, Crassatel- 

 lites, Cucullcea, giant Lima, Meretrix, giant Venericardia, 

 Ancillaria, giant Conns, Cassis, Murex, Rimella, Strombus, 

 Terehellum, Turhinella, Volutilithes, true Nautilus, spatangoid 

 sea-urchins, and cidaroids (absence of all ammonites, Inocer- 

 amus, belemnites, Exogyra and Trigonia). No climatic zones, 

 and faunas not yet provincial. 



OLIGOCENE. 



Survival of many Eocene genera, but appearance of more 

 modern types; modern groups of Pecten, especially Chlamys; 

 Spisula, Panopcea, Phacoides; modern groups of VeneridcB, 

 especially Chione and MacrocaUista; Agasoma, Dolium, Mio- 

 pleionia, Priscofusus, Molopophorus, Strepsidura, Turcicida, 

 Aturia. First appearance of modern species of MoUusca: 

 Panopcea generosa, Macoma nasuta, Thracia trapezoidea, 



