68 CALIFORNIA ACADEMS OF SCIENCES. 



American species, Lncina acutUineata, Cylichna alba, and Pecten caurinuK. There 

 are many such cases of the similarity of species, and in a few instances identical 

 species have been found which are common to the two regions. The following species 

 are found in Dr. Brauns' list of upper Tertiary fossils from Ojai, near Tokio, which 

 are also found in the San Pedro deposits: 



List of Fossils from Ojai, which are Found in the San Pedro Deposits. 



Cardium californiense [= C. corbis] Kellia suborbicularis Panopea generosa 



Crepidula aculeaia Macoma nasuta Tresvs nnttalU 



Among the species now found living in Japan, and on the west American 

 coast, and also found in the San Pedro deposits, are the following:' 



List of Living Species Common to Japan and the West Coast of North America, 

 which are Found in the San Pedro Deposits. 



Cardium corbis Macoma nasuta Sanguinolaria nullalli 



Crepidula grandis Macoma secta Siphonalia hellettii 



Cryplochiton stelleri Mylilus e.dulis Tresus nutialli 



Dentalium he.xagonum Natica clausa Tapes slaminea 



DrilUa inermis Pecten hericeus Tellina bodegensis 



Leptothyra carpenteri Purpura crispata Tritonium ("= Priene) oregonensis 



Macoma edulis Panopea generosa Trophon orpheus ( = T . sluarti (1) ) 



Macoma inquinata Pododesmus macroschisma 



The living faunas of the Japanese and west American coasts, though having 

 many species in common, are not as closely related as are the uf)per Tertiary and 

 Pleistocene faunas of the same regions. This has been brought about in two ways. 

 First, the more or less close connection between the two regions, which existed in 

 late Tertiary and early Pleistocene times, has been broken; and second, southern 

 species from the warm China seas have migrated northward and mingled with the 

 Japanese early Pleistocene species, while Panama sjjecies have come northward 

 during the upper San Pedro time and changed the aspect of the fauna of the west coast 

 of North America. Those species which Japan and the west coast of North America 

 have in common are either circumboreal or are forms which have changed little since 

 the habitats of the two faunas were similar and connected; those species which differ 

 but slightly have in many cases made this change since the connection was broken; 

 and many of the forms which occur in each fauna, and which have no counterpart in 

 the other, have come into these faunas in comparatively recent times. 



An interesting example of the migration which took j^laee between Japan and 

 western North America is offered by the genus Haliotis. This genus is of Asiatic 

 origin, but it migrated to the northern American coast during late Pliocene or early 

 Pleistocene times. This is shown by the absence of this species from any of the pre- 

 Pleistocene formations along this coast. Only two fossil Haliotidre have been found 

 on this coast, one being taken from the upper San Pedro (Pleistocene) gravel of 



' This list l8 compiled from the following papers : 

 Molluakii of WoHtorn North America. By P. P. Carpenter. Smithsonian Miscellaneous Collections, No. 252, 1872. 

 CatalOKue of California Fossils. By J. a. Cooper. 7th Ann. Kept. Cal. State Mineralogist, 1888. 



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