JOURNAL OF THE COLLEGE OF SCIENCE, IMPERIAL UNIVERSITY, 

 TOKYO, JAPAN. 



VOL. XVII. ARTICLE, 12. 



On the Fossil Echinoids of Japan. 



By 



S. Tokunaga {formerly Yoshiwara), 

 RigakuhakusM. 



With 4 plates. 



Although the number of fossil echinoids hitherto found in 

 Japan is small, yet there are several interesting forms amongst 

 them. The Palaeozoic strata has yielded no echinoids, while in 

 the Mesozoic five genera have been found, one of which, however, 

 is doubtful. They are Pygurus, Toxaster, Cidaris, Pseudocidaris, 

 and Hemicidaris (?). Pygurus, up to the time of its discovery 

 in Japan, had been found only in the Oolite and Cretaceous of 

 Europe, and in the Cretaceous of Northern and Western Africa 

 and N. America (?). In Japan it is found in the so-called 

 Torinosu-limestone, respecting which it is still uncertain whether 

 it is Cretaceous or Jurassic. One feature, however, that leads us 

 to think that it may be Cretaceous, is the presence of a species of 

 Toxaster, which has been hitherto restricted to the Cretaceous of 

 Europe, N. Africa and Asia (Syria). Many specimens of Cidaris 

 and Pseudocidaris have been collected from the same limestone, 

 and also from a similar one in several other localities such as 

 Tokano and Yokodani in the Province of Tosa and Itsukaichi in 

 the Province of Musashi. 



