24 ART. l.-S. YOSHIWAEA. 



There are muny spscies of Foraminifera and Radiolaria. Textiilarla, 

 Amphistcgina, TrilociiUna, Planorhilina , Fiotalia and Glohigerina have 

 been collected from Shuri ; Eotalia and Aniphistegina from the 

 Foraminiferal sand of Yomura in Oshima. A gigantic Opercidina 

 (PI. I) is found numerously in the reefs of Okinawa-jima, Tokuno- 

 shima and Okinoerabu-jima, and is always well preserved. 



From the above description we may draw the following conclu- 

 sions : — 



1. The raised reefs in the Riukiu Curve are mostly later than 

 the Tertiary, and are overlaid by recent rocks. 



2. These reefs are horizontal, in contrast to the inclined beds of 

 the substratum. 



3. In the ancient time they either covered the rocky sea-bottom, 

 or fringed the margins of islands. 



4. The northern limit of the ancient reefs in the western Pacific 

 is 29° X.L. 



5. The maximum elevation of the raised reefs in the Riukiu 

 Curve is 684 ft. 



6. They are distinguished from the recent reefs by their position, 

 structure and colour. 



7. The raised reefs are often found in the shape of terraces. 



8. The reefs exhibit a character like those now growing under 

 the sea water of the same region, and have been upheaved after a 

 gradual depression. 



October 1900. 



