76 



LA TOUCHE : GEOLOGY OF NORTHERN SHAN STATES. 



Several specimens of Orthis subcrateroid.es Reed and 0. irravadica 

 Reed were also obtained from a small outcrop of these beds near 

 the village of Umong (Loc. 98, E 2), about a mile south of Kunkaw. 



On the eastern side of the ravine fossils were collected from a 



band of buff-coloured marlv sandstones on the 

 Fossils, Nam-yun. . . , , T 



ascent from the stream to .Nam-yun (Loc. 



99, E 2). These included Rafinesquina imbrex Pander ; R. subdel- 



toidco, Reed ; Plcctambonites sericea Sowerby, a characteristic Ordo- 



vician species with a very wide horizontal range, commonly known 



as Leptcena sericea ; Orthis irravadica Reed ; 0. subcrateroides Reed ; 



and Clitamlioiiitcs cf. squamata Pahlen, the type of which occurs 



in the Echinosphaerite limestone of the Baltic Provinces. 



Beyond this there occurs another gap, in which the lower Naung- 



kangyi beds have not been found, though 

 tion^Pktem^' the y Probably come to the surface in the 



deep, trackless valley of the Nam-Sam, since 

 they are found on the Panghsa-pye saddle (F2), where there is a 

 fairly good exposure at the village. Here they contain Ort/iis 

 subcrateroides Reed, 0. testudinaria Dalman, and large numbers of 

 the plates of Caryocrinus sp. Between this and the valley of the 

 Nam-Tu near Lilu they are concealed or cut out by the great over- 

 thrust fault mentioned on page 55, but they reappear in the deep 

 ravines entering the main river from the north-west. A good outcrop 

 was found in the valley of the large stream joining the Nam-Tu at Lilu 

 (Loc. 103, F 1), about a mile above the village, and yielded a large 

 number of fossils. The rock here is identical in appearance with 

 that at Chaungzon, and the fauna is very similar, Orthis, especially 

 0. subcrateroides Reed, being the most common form. The other 

 fossils collected here included plates of Heliocrinus sp. and Caryo- 

 crinus sp. ; Rhinidictya cf. plumula Salter ; Rafinesquina imbrex Pan- 

 der and R. subdeltoidea Reed ; Orthis testudinaria Dalman ; 0. ir- 

 ravadica Reed ; Plectambonites sericea Sowerby ; and fragments of 

 trilobites, consisting of indeterminable, single thoracic segments, some 

 of large size. On the spurs between the ravines the lower Naung- 

 kangyis are concealed by higher beds. The most northerly point 

 at which they have been found is in the valley of the Nam-pang- 

 yun, between the Bawdwin silver mines and the Nam-Tu, beyond 

 the limits of the map ; but no collections of fossils have been made 

 from this locality. Fragments of trilobites are very numerous at 

 particular horizons but are quite indeterminable. 



