SILURIAN SYSTEM : UPPER NAMHSIM STAGE. 



The most striking feature about this list is the large number 

 of species !\ that have already been described, 



Paucity of new species. 49 ■ . , . . . 



or are soj closely allied to known lorms that 

 they do not require new names. Among the 24 determinable species 

 Mr. Cowper Reed has found it necessary to give names to only 

 three, whereas of the nine determinable species of the lower Namh- 

 sims four, or nearly half, were new. This greater similarity, how- 

 ever, in the fauna of the upper Namhsims to that of the Silurian fauna 

 of other regions is perhaps more apparent than real, and may 

 be due merely to a greater similarity of environment in the case of 

 the upper beds, since these correspond more closely in lithological 

 character to the calcareous beds of the Silurians of Europe. 



The upper Namhsim beds have not been found close to the 

 western edge of the plateau, but make their first 

 Distribution : West- ap p earance along the crest of the Pyintha ridge, 



ern edge of Plateau. rr ° _ J 0 ' 



the second considerable rise on the way from the 

 plains up to Maymyo. They may be present at the base of this ridge, 

 about a mile east of Zebingyi station (Loc. 39, B 5), where an outcrop 

 of the Zebingyi beds with graptolites is exposed in a low cutting, 

 resting on some marly beds containing Orthoceras and the pygidia 

 of Phacops shanensis, but the ground between this cutting and 

 the base of the ridge is so overgrown with vegetation that nothing 

 more can be seen of the rocks. At the top of the ridge the marls 

 are exposed on the cart road in a dip at the 32nd mile just before 

 reaching the village of Kyinganaing (Loc. 43, B 5). Here the 

 only fossil found is the trilobite Phacops shanensis Reed, but it 

 occurs in large numbers, and though the rock, a bright yellow 

 marl, is exceedingly soft, the specimens, when first broken open, 

 are quite well preserved, though the details are apt to be quickly 

 rubbed off. The species belongs, according to Mr. Cowper Reed, 

 to Phacops sens, str., which is characteristic of the Devonian, but 

 also occurs in the Silurian. A variety of Ph. fecundus Ban., from 

 the ' Hercynkalke' of the Harz, is perhaps identical with this species. 

 The pygidia of the same species are rather common in the cutting 

 east of Zebingyi station mentioned above, and in a small exposure 

 in a watercourse at the side of the cart road about a mile west of 

 Pyintha, just at the crest of the ridge. 



Further on the marls have not been detected for a very long dis- 

 tance, probably because they are so apt to be erod- 

 Plateau! ern ° <lg " ° f °^ anc * concea ' e d hy surface wash and vegetation. 



The next place at which they are known to occur 



