ORDOVICIAN SYSTEM: LOWER NAUNGKANGYI STAGE. 75 



stones interbedded with greenish micaceous sandstone, the fossils 

 occurring in the latter. The fauna is particularly rich in specimens 

 of Orthis and the whole facies of the deposit is very similar to 

 that in which the Caradoc fossils of Shropshire occur. The collec- 

 tion from Chaungzon includes Heliocrinus sp., the same detached 

 plates that are found at Tawmawgon, etc. ; Echinoencrinus aff. 

 Senckenbergi v. Meyer ; Orthis calligramma Dalman ; 0. (Dalmanella) 

 testudinaria Dalman ; 0. (? Dalmanella) chaungzonensis Eeed ; 0. 

 (Dinorthis) flabellulum Sowerby ; 0. irravadica Heed ; and 0. sub- 

 crater oides Reed. 



Detached plates only of the Cystidean Echinoencrinus aff. Senck- 

 enbergi occur, resembling in sculpture and ornamentation those of 

 the type species of the genus from the lower Ordovician of northern 

 Europe. Orthis calligramma and 0. flabellulum are both well-known 

 and characteristic fossils from the Bala or Caradoc beds of Britain. 

 0. thakil Salter, from the Ordovician of Niti, 1 is probably allied 

 to 0. flabellulum. Of the two new species, — 0. chaungzonensis is allied 

 to 0. argentea Hisinger, and bears a considerable resemblance to the 

 variety of 0. thakil from Niti named subdivisa by Salter ; 2 while 

 0. irravadica seems to be closely allied to 0. moneta Eichw., from 

 the Russian Ordovician. 



To the east of the Gokteik gorge the lower Naungkangyi beds 

 , . are again concealed for a long distance, being 



overlapped by higher beds in the valley of the 

 Nam Tang, which joins the Nam-panhse at Chaungzon, across the 

 divide which separates this river from the Nam-hsim, and in the 

 valley of the latter river. They reappear however, on the sides 

 and floor of the deep ravine of the Nam-non, a tributary of the 

 Nam-hsim, east of the village of Kunkaw (E 2). A few fossils 

 were collected from them at a point on the path leading up from 

 the Nam-hsim to Kunkaw, about a mile south of the village, in- 

 cluding Escharopora sp., a bryozoan ranging from the Birdseye lime- 

 stone to the middle of the Cincinnati group of America (middle to upper 

 Ordovician) ; Orthis irravadica Reed ; and Calymene birmanica Reed, 

 a trilobite resembling very closely C. parvifrons var. Murchisoni 

 Salter, from the lower Ordovician of England, 3 and in some respects 

 also C. nivalis Salter, from the Ordovician of Niti. 4 



1 Palasont. Niti, p. 39, PI. IV, figs. 8, 9. 



2 Ibid, p. 41, PI. IV, figs. 11, 12. 



8 Mob. British Trilobites, p. 102, PI. IX, fig. :>G. 

 4 Palseont, Niti, p. 10, PI. I, fig. 24. 



I 



