SILURIAN SYSTEM : UPPER NAMHSIM STAGE. 



145 



the outcrops at the two localities, and the discrepancies can only 

 be accounted for by local variation in environment. This is also 

 indicated by the apparently very restricted distribution of the Manaw 

 fauna, which has been met with only in this one locality, and by the 

 very small thickness of the layer in which this fauna is contained. But 

 it is easy to see how such a thin band of rock might escape de- 

 tection in a district where the rocks are so concealed by super- 

 ficial deposits as they are on the Shan plateau, and such a dis- 

 covery as this, due one may say to an accidental blow of the hammer, 

 shows how much there is still to be learned by patient search, 

 before the relationships of the isolated outcrops described in this 

 Memoir can be worked out. 



The upper Namhsim beds have been recognised on the eastern 



slopes of the hills north-west of Hsipaw, on the 

 North-easterly extension. „ . , . . ... 1 . 



path to ranghsa-pye, above the village ot Man- 



hpeklu (F 2), but only fragments of trilobites and small brachio- 



pods were found here. They also occur along the crest of the 



scarp east of the Nam-Tu gorge, further to the north, and are 



seen just above the mouth of the Nam-pang-yun or Bawdwin river, 



where they contain large numbers of Orthis elegantula ; but the 



beds are generally much concealed, and no fossiliferous localities 



comparable to those of Konghsa or Manaw have been found in this 



direction. Indications of the presence of these beds are to be 



seen, however, in almost every instance when the boundary between 



the Namhsim Sandstones and the Plateau Limestone is crossed, and in 



spite of its small thickness, the band seems to be remarkably persistent. 



The same remarks apply to the development of these beds in 



^ „ the Eastern Ranges. They are to be met with 



Eastern Ranges. ° » 



whenever the boundary between the Plateau 

 Limestone and the underlying rocks is exposed, though the thick 

 Namhsim Sandstones appear to be absent in this area. Fossils are 

 T . T not numerous, but specimens of the Fenestella 



Loi Lcn Rang. , , 



so abundant at Konghsa were found in more 



than one place along the crest of the Loi-len range, and also 

 further to the north-east, near the village of Panghsa-pui (Loc. 61, I 1) 

 These beds are found all along the eastern base of Loi Ling, form- 

 ing a narrow fringe at the edge of the limestone plateau, and in 



.... „ , the dome-shaped range of hills to the east, 



Mong-Iveng dome. . x m , 



between the lertiary coal-field of Man-sc-le 



and the plateau of Mong-Keng, they occupy very large areas both 



