20 Art. 6. — M. Yokoyama: 



Fuchi and Yamagayado) in Kami-Miyata and four localities (Maru- 

 yama-no-Saka, Harashita, Matsubara and Motoyashiki) in Shimo- 

 Miyata. 



The number of species collected in the above-named places 

 amounts to 238 in all, as will be seen from the foregoing table: 



A glance at the table is sufficient to show that we have here 

 a fauna which has lived in a shallow sea. The lithological 

 character of the. fossil-bearing rock in some places also points to 

 the same conclusion, for example, as at Koshiba where it is partly 

 a conglomerate. 



Among the species above enumerated, there are 3 which are 

 not well determined. But, even if we deduct these 3, there still 

 remain 235 species, a number which, I believe, is enough to give 

 quite a fair idea of the general character of the entire fauna. 



In the first place, what is very important in the fauna from 

 the geological point of view is the percentage of the extinct forms 

 against the living. The number of those forms which are hitherto 

 not known to be living amounts to 88 species or about 37% of the 

 whole fauna. This is a percentage which is considerably greater 

 than that ascertained. in the Mollusca of the Upper Musashino. 1} 

 And among the living, there are still 7 species which have not yet 

 been found in Japanese waters. They are the following: 



1. Volvula acuminata (Brug.). Habitat: Suez, Atlantic. 



2. Mitra chenu* Lam. Habitat: Atlantic (inch Mediter- 

 ranean). 



3. Calyptrœa mamillaris Brod. Habitat: West Coast of 

 America. 



4. Lima subauriculata Mont. Habitat: Atlantic (Greenland 

 to Mediterranean). 



5. Pecten tigerrinus (Müll.). Habitat: Atlantic (Norway to 

 France). 



6. Leda ramsayi Smith. Habitat: New South Wales. 



1) Tokunaga in his "Fossils from the environs of Tokyo " p. 95 says that there are at 

 least 10 extinct species among 165 which he enumerated, though I think the real number 



is somewhat greater. 



