ORDOVICIAN SYSTEM : NAUNGKANGYI STAGE* ^5 



the Llandeilo and Bala beds of Northern Europe and, though they do not 

 help us to fix more precisely the horizon of the beds in whioh they are found, 

 yet indicate the same zoo-geographical affinities of the Burmese Ordovician 

 fauna. The fragmentary cystidean remains from all the fossiliferous localities 

 point the same way. The only anomalous form is Ariatocystis, whioh is 

 typically a Bohemian and South European genus." 1 



Summarising the results of Mr. Cowper Reed's researches, as 

 Affinifes of fauna contained in the two Memoirs contributed by 

 him to the Palaeontologia Indica, we find 

 that he has described 124 species from the Ordovician rocks of the 

 Central Himalayas, and 47 from those of Burma. Of the former 

 52 (42 per cent.) are allied with American species, while only 31 

 (25 per cent.) may be compared with European forms. Of the lat- 

 ter, on the other hand, 13 species (27 "7 per cent.) have American, 

 while no less than 30 (66 per cent.) have European affinities. 

 Furthermore, it should be noted that while among the Himalayan 

 species only one, Plectambonites sericea, is identical with an American 

 form, and only two, PI. sericea and Orthis porcata with European 

 species, — even such a cosmopolitan form as Orthis (Dalmanella) test- 

 udinaria being represented by a variety ; — the Burmese fauna ex- 

 hibits a far closer connection with that of Europe, no less than 10 

 species being identical. Comparing in the same manner the Him- 

 alayan with the Burmese fauna, we find that of the 124 species of 

 the former only 11 (9 per cent.) are allied forms, and that only 

 three of the peculiar forms, Rhinidictya plumula, Plectambonites 

 repanda, and Pliomera ingsangensis, appear to be identical, though 

 of this little trilobite Mr. Cowper Reed says : — 



" It must be remembered that this supposed link only rests on one im- 

 perfect pygidium from Niti.2 " 



The only other identical fossil is the ubiquitous Plectambonites 

 sericea. 



But it is when we consider the composition of the faunas that 

 the most striking discrepancies between the 



fau C na mP0SitiOn ° f ^ H i mala y a « ™ d the Burmese areas appear. 



One of the most marked characteristics of the 

 Naungkangyi beds is the extraordinary abundance of the remains 

 of Cystideans, not always well preserved, it is true, but so 



1 Lower Palaeozoic fossils of the Northern Shan States, Burma : Pal. Ind., New 

 Series, Vol. II, Mem. No. 3, p. 85. 



? Of. cit„ Pal. Ind. Scr, XV, Vol. VII, Mem. No. 2, p. 166. 



I % 



