vor. 



59^,)"'] PROCEEDINGS OF THE NATIOxNAL MUSEUM. i77 



water assembly. J^'auiially the species point to a distinct analogy with 

 those of the Cliiiia and Soutli Jajmn seas, and, like the existing fauna of 

 those seas, they indicate ])onds of i-elationship with tlie west coast of 

 Africa and the coast of Australia ratlier than with the Indo -Pacific 

 fauna of northeast Africa and the Malay Archipelago. These curious 

 analogies have been noted ])y all those who have studied the mollusk 

 fauna of Japan, and their explanation is one of the trojihies for which 

 future students, with fuller geological knowledge of oriental countries, 

 may compete. At present hypothesis could rest only on speculation. 



It is not often that so small a number of specimens as those we have 

 described would cojitain the elements Ji(;cessary. for deciding on so 

 many points of interest, but the present case is a fortunate exception. 



We may now consider the climatifj relations indicated by tliis little 

 collection. There are no observations on i(;cord from the Gulf of Pen- 

 jinsk, but the climate can differ but little from that of Okhotsk, which 

 IS situated in the sain*', latitude as tliat of the mouth of theOulfof Pen- 

 jina and some 350 mih's to the westward. If there is any difference it 

 is that the gulf is colder than Okhotsk, since Scammon indicates that 

 open water occurs a])out June 20 in the gulf, wliile tin? average at 

 Okhotsk is abouf two weeks eai'lier. 



We find Okliotsk has a mean annual temperature of the air of 23.1'^, 

 spring having a mean of 23.9'^, suiMm(!r of 52.1/^, autumn of 24.6'^, and 

 winter of minus 8.2''-'. Th<! tem])eraUiie of the sea water does not rise 

 above 40*^ F. (except in the harbor) during the warmest part of the 

 summer, and foi- two-thirds of the year it is at or below the freezing 

 point. It may therefore be assumed that the water climate of Pen- 

 jiusk Gulf does not essentially differ from that which is offered by 

 those parts of the Polar Sea which are free from ice during the summer 

 months. The climate of the region indicated as a natural (jjimatic home 

 by such an assemblage of fossils as those we liave been discussing, 

 should have a summer sea-water average temperature of TC^, and a 

 winter average of 00'^ F. at least, with a minimum temperature never 

 api)roaching the freezing ])oint. As the difference between the tempera- 

 ture of the air and that of tin*, water can not permanently remain 

 much greater than 5^ or VP^ it follows that the annual mean tem- 

 perature of the Gulf of Penjinsk in Miftcene time (f)r the era indicated 

 by our fossils) can not have been much less than OC^ F., and was prob- 

 ably highei\ That is to say, since this fossil fauna flourished in these 

 waters the annual mean temi)erature has diminished by SC^ to 40'^ F., 

 at the most modc^rate calculation. 



It is peihaps very late in the day to refer to the hypothesis which ex- 

 plained the warm water Old MuH-ane of the north Atlantic shores by 

 assuming a sliiltiiig of the ])(dar axis so that the pole at that time would 

 have been situated somewhere in central Siberia. That hypothesis has 

 few if any friends at the present time. But it may not be amiss to point 

 out that, if it were necessary to put a quietus on that moribund specu- 



