416 Journal of the Asiatic Society of Bengal. [NS., XIV, 
the Pegus, and do not forma recognizable horizon separating 
them from the Irrawaddies. In the middle of the Irrawaddy 
basin, a fairly constant and well developed red earth bed has 
been chosen as the boundary between the Irrawaddies and 
Pegus, because it isan easily mapped horizon, and in Yenangy- 
aung, the ONLY horizon which can be mapped with confidence. 
Assuming then that this red earth bed was the same as 
that found on the road to Ngape from Minbu, I drew a 
boundary-line between the Pegus and the Irrawaddies. This 
boundary was traced by my colleague the late H. 8. Bion north 
to Pakokku, but it became confused by the appearance of 
other red beds, and by its poor development in certail 
places in the north Minbu area. North of Pauk in Pakokku, 1 
found that the horizon entirely failed; the beds above and 
below being ordinary freshwater sandstones of exactly the 
Same appearance as the Irrawaddies of Minbu. That these 
The emergence of land locally through silting uP os 
deep-sea, or conversely of deltaic facies, and a less local Seni 
of certain stratigraphical gaps. This does not affect thee 
point at issue, for there is no evidence of any ave all 
sea at the horizon of the Pegu-Irrawaddy boundary xt | 
evidence, as I have stated, pointing to a gradual meee 
A second point no less important should oo f 
ed. the Irrawaddy Basin there are numerous the form — 
anticlines, minor folds, developed subsequently % 
Geol. Sit 
l Piinsin & oe ner —— Be 
Ind., XLVI, p. ee : Eocene Mammals from 
