SILURIAN — MAGNESIAN SANDSTONE. 87 



Jutdna, close search led me to the discoveiy o£ some little bivalves 

 numerously scattered through a small thickness of the sandy micaceous 

 shale. The shells are very thin, no pair ever occurring in position, and 

 are frequently crushed, flat, and broken. With great care and trouble 

 Dr. Waagen was able to free the internal aspect of a few of the valves 

 (the outside only being visible in some hundreds of specimens) so as 

 to enable them to be determined as belonging to two species of Oholus 

 or Siphonotreta, genera only found in silurian rocks. The discovery of 

 these led to the hope that some other fossils might be detected, but nothing 

 except fucoids or annelid markings has been obtained by further search, 

 and I was obliged to rest content with the proof that the Salt Range 

 contained even older palseozoic rocks than the carboniferous formation 

 . discovered by Dr. Fleming. 



This silurian sub-division is well defined on Mount Tilla, Chambal 



T,, , , Mountain (east), on the north-west side of Diljaba, 



Places where seen, and » / j j 



definition. from Jalalpur to Khewra, and thence to Makrach^ 



but beyond this westward becomes divided by light-coloured sandstone 

 bands and loses much of its definite appearance. The characteristic shaly 

 portions can nevertheless be often recognised (though of a greener 

 colour), bending into the gorges and forming the middle of the cliffs as 

 far as the Sungle Wan north of Nalli. 



In a few places — as, for instance, along the track from the Verala 

 springs to Pail — conglomeratic bands occur in this group, the included 

 pebbles being small, and as is usual in all deposits of the range older 

 than tertiary, being exclusively of crystalline rocks. The thickness of 

 the group varies from twenty to one hundred and fifty feet. 



Magnesian sandstone group. 



No. 4. — The next group above that with silurian fossils presents a 



strong contrast to it, and in a great measure 

 Character. . . . „ , 



owing to the association of the two, forms some of 



the most marked cliff features of the escarpments of the range. In this 



character it replaces the nummulitic limestone wherever the latter is 



( 87 ) 



