^54 Journal of the F.M.S. Mmeums. [Vol. VI. 



S. W. to N. E. The sandstone is of varying stages of hard- 

 ness and at the summit of the island is soft and crumbly 

 (pi. XXXVI. , fig. 2). Where it has weathered it is cut down 

 to about sea-level and what were once larger islands now 

 consist of a group of several smaller ones connected by a 

 sandy gully or standing on a common reef awash at low tides. 

 There appears to be no coral in the vicinity. C. Boden Kloss.] 



Sedimentary rocks from Pulau Jemok, 

 OR Long Aroa. 



Specimens of sandstone and shale from Pulau Jemor 

 were sent to me in February, 1915 by Mr. H. C. Robinson. 

 They are grey shale, light coloured sandstone, and a slightly 

 coarser sandstone, partly stained red, and containing small 

 white angular fragments which suggest kaolinized felspar, but 

 which are in reality derived from a weathered rock containing 

 micro-organisms. 



The shale contains minute flakes of mica and resembles 

 the grey shales found in several localities of the Peninsula. 

 The specimens do not show any organisms. 



Thin sections mounted for examination with the micros- 

 cope are necessary to see the micro-organisms in the white 

 angular fragments of the sandstone. As the sections are not 

 very translucent, bright illumination is necessary, and then 

 only a few fragments show the organisms clearly. They are 

 all radiolaria, sometimes showing the reticulation of the test 

 plainly but never sufficiently well preserved for specific 

 determination. 



Fragments and pebbles of a similar radiolarian rock are 

 common in the coarse quartzites of the Peninsula, where 

 they have been almost certainly derived from certain radio- 

 larian cherts found in situ. The quartzites, as far as is known 

 at present, are all Mesozoic, fossils having been found in 

 Perak, Pahang and Singapore, and the fragments in the Aroa 

 rocks suggest that they may be an extension of the Peninsula 

 rocks. If opportunity offers, the grey shales should be 

 searched for Estheriella, a small fossil difficult to detect, that 

 occurs in Perak and points to brackish or fresh water condi- 

 tions during the Trias, when the shales were laid down. 



Mr. Robinson describes the rocks on Pulau Jemor as 

 highly inclined. One of the photographs (PI. XXXVI, fig. i) 

 shows this. 



