YENANGYOUNG. 



57 



the upper part calcareous concretions of various irregular shapes 

 resembling fossil roots or bones, are very common. 



Of more subordinate importance are beds of ferruginous conglo- 

 merate, generally forming thin and irregular layers, which resemble 

 shingle deposits. The thickest of these beds is found at the base 

 of the division, where it forms a very constant horizon, which I shall 

 have occasion to describe further on. 



Still more subordinate are argillaceous beds ; now and then they 

 form layers of some thickness, but generally they occur in thin beds ; 

 their colour is a greenish brown of various shades. 



(b) Palasontological characters. — Near Yenangyoung the Ira- 

 wadi series contains numerous specimens of bones and teeth of 

 vertebrates. The specimens are particularly common along the river 

 bank between Yenangyoung and Nyounghla, but fragments may be 

 picked up almost everywhere in the more conglomeratic beds. 



As I have discussed the relations of this fauna in a previous 

 paper, 1 it is superfluous to go over the same ground again. It will 

 suffice to say that the species determined, excepting those which 

 are indigenous to Burma, are all identical with Siwalik species. 



With regard to the recurrence of species I may mention that frag- 

 ments of Crocodilis sp. (cf. biporcatus) and Gavialis (cf. gangeticus) 

 preponderate. In fact there is hardly a conglomeratic bed in which 

 at least a few fragments of these two species may not be found. 

 Next come Chelonian bones, in particular Trionyx sp. Then 

 follow the other animals, among which Hippopotamus irravadicus, 

 Acerotherium perimense, Mastodon cliftii are more frequent than the 

 other forms, which are generally very rare. 



In conclusion I may say that the specimens are very irregularly 

 distributed ; the river bank between Yenangyoung and Nyounghla, 

 along which in former years such rich collections have been made, 

 barely yielded a few fragments in 1895. 



1 The Development and Subdivision of the Tertiary system in Burma. Records 

 of the Geol. Surv. of India, 1895, XXVIII, pp. 59-86. 



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