14 KOTO : KOTES ox THE GEOLOGY 



hardened foramiiiifer sand {PL II, Fig. 0.) of Eecent age ; frag- 

 ments of corals, bivalves and serpula mixed witli otlier components. 

 The foraminiferal rock consists of millions of discoidal and 

 spiral, water-worn shells. Karely they have spines well-preserved. 

 Viewing a section of the shell under the microscope, it is seen 

 that the test consists of the tubulated proper walls of chambers, 

 besides the canaliculated intermediate skeleton which forms 

 spur-like marginal appendages, characteristic of Calcari/ia, and 

 its external form and microscopic details agree well with C. 

 Spenglei'i, Linné'\ dredged for the first time near the coast 

 of Amboina at the depth of 1,42.") fathoms. This species seems 

 to be cpiite as abundant in the East Indian Archipelago, as we 

 find here in the Pescadores. By wear and tear of rolling waves, 

 the surface of the test becomes smooth, and the presence of spines 

 can be usuallv only recoonized in examinins; the structure of the 

 supplementary skeleton which points to the former existence of 

 some sort of prominence. 



GIO-Ô ISLAND. 



Gio-o, or Fisher Island, lies to the west of Hôko, and 

 encloses with the latter the head-less Bay of Hôko, or rather 

 an arm of sea. What has been said of other islands as regards 

 the geology and the topography, holds true also of Gio-o, with 

 the differences, that the island is really table-shaped, bounded 

 on all sides by cliffs, leaving no space for .Vlluvial deposits, 

 excepting the shore and fringing reefs ; and that the igneous 

 sheet as well as the interbedded sedimentaries are developed to 

 their full advantage, thus affording the best opportunities for geolo- 



1) Chullcn-'jor Report, ' Foraminilera.' 



