112 LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



In the foregoing table I have left out of account those genera 

 and species that have been only provisionally determined by Mr. 

 Copper Reed, though it is obvious that the occurrence of such 

 trilobites as Asaphus, Lichas, Brovteopsis, Ampyx, Harpes, and 

 Agnostus, rnd of such characteristically lower Ordovician forms as 

 Phacops (Pterygometopus) Panderi and Asaphus {Ptychopgye) Law- 

 rowi confirm in the clearest manner possible the general conclusions 

 already formulated regarding the age of the Naungkangyi forma- 

 tion, that it corresponds with the Ordovician, Llandeilo and Cxraioc 

 or Bala groups, of Europe. 1 



Before proceeding to a discussion of the affinities of the fauna, 

 it may be well to offer some remarks on its 

 thefa C uL diStribUti0n ° f local distribution, which presents some peculiar 

 features. And here I must repeat my former 

 statement that the conditions of the country are such that it is 

 extremely difficult to connect any one of the isolated exposures of 

 rock with another except on lithological grounds, or to ascertain 

 whether the fossils collected at any given spot are on the same 

 horizon or not as those found in lithologically similar beds at 

 another locality. Even where a rich fauna occurs it is often im- 

 possible to be quite sure to what horizon it belongs, owing to the 

 extraordinarily isolated and unique character of the exposures. 

 Thus the rich Cystidean fauna of Sedaw, described by Dr. Bather, 

 has only been found at that one spot in the Shan States, and the 

 only stratigraphical reason for supposing that it belongs to an 

 horizon low down in the series is the fact that it has not been 

 observed in other places where a comparatively complete sequence 

 of rocks can be seen ; the presumption being that if it does exist 

 elsewhere, it is overlapped by higher beds. 



For these reasons it is impossible to treat the fauna of the 

 Naungkangyi beds otherwise than as a whole 

 Local range of for ^ present) including in the discussion 



species. * 



the fossils both from the upper and lower 

 groups. For if we leave out of account the cystideans from 

 Sedaw, we find that of 14 determinable species described from the 

 upper Naungkangyi beds, no less than 10 are also found in the 

 lower group. No doubt, when the fossils hitherto undescribed. from 

 the upper group, are worked out, the discrepancy will appear much 



1 Y. R. Cowper Reed, Pre-Carboniferous Life- Provinces, Records, Qeol. Kurv. Ii.d., 

 Vol. XL, Pt. 1, p. 22. 



