﻿618 ME. L. V. DALTOIS" ON THE [NoV. I908, 



of the Bassein Group in the west of the Minbu and Thaj'etmyo 

 districts, in ascending order : — 



(1) Turritella-ZonQ. A ferruginous calcareous sandstone or impure lime- 



stone, thickness unknown, with numerous fossils, often full of shells 

 of Turritella (see p. 612). 



(2) A thick series of shales and sandstones (with petroleum in some of the 



sandstones, and carbonaceous material), with fossils at Subagyidan 

 up to about 60 feet above the top of (1) (see p. 613), Venus granosa 

 2 miles west of Myegya, about 4000 feet above (1) (p. 612), Ostrea 

 yomaensis at an horizon above this (p. 611), and sandstone with 

 AmpuUina spherica, etc., close to the top (p. 612) 6000 feet. 



(3) Zone of AmpuUina grossa. A grey impure limestone or highly- 



calcareous sandstone with large shells of this species (p. 612) 



Thickness unknown, but variable. 



(4) Shales and sandstones, the latter often bituminous. Ampxdlina 



ponder 08a occurs near the top of these (p. 612) 2000 feet. 



(5) Zone of Corhula harpa, in blue clays found near Magyisan (p. 612). 



Thickness (?). 



(6) Zone of Hydrozoa (p. 612) 6 inches. 



(7) Shales and sandstones 100feet(?). 



(8) Zone of Kummulites Beaumonti (?), red, impure, very shelly limestone 



(p. 612) 25 feet. 



Giving a total thickness of 8125 feet or more. 



The thicknesses tabulated above are all the least possible, so that 

 we must either assume that the 1200 feet estimated by Theobald 

 increases very greatly northwards, or that the upper 7000 feet or so 

 of the so-called ' Chin Shales ' of Dr. J^Toetling are here fossiliferous, 

 and must be included in the Bassein Division of the Eocene, which 

 seems the more probable solution, since this group has never been 

 properly studied. This leaves 3000 feet, according to Dr. Noetling, 

 for the Chin Division, the age of which is not known ; but part of 

 it probably belongs to Theobald's ' Axial Series,' of the subdivision 

 of which something has already been said. It is suggested, there- 

 fore, that, to accord with our later knowledge, the name of the 

 Chin Division be dropped, leaving only the Bassein and Pegu 

 Divisions for the Arakan Series, the former with a much increased 

 thickness ; and constituting as the Axial Series all those rocks 

 below the (as yet) unseen base of the Bassein Stage. 



Passing now to the new data regarding the Pegu Stage, there 

 is no need to review in detail the stratigraphical relations of the 

 various fossils found in the upper portion ; but the relations of 

 the fossiliferous horizons of the lower beds may be conveniently 

 considered here. In the Thayetmyo district the following horizons 

 were observed below the zone of Cytherea erycina (see p. 608) : — 



(1) 150 feet below, sandstones and shales with Lucina glohiilosa, Desh. 



and Balamis tintinnabuhton, Linn. 



(2) 250 feet below, sandstone with Turritella acuticarinata, Dunk., and 



Voluta (!) birmanica, sp. nov. 



As Lucwa glohulosa has not hitherto been found in Burma, it is 

 perhaps permissible to name the second bed the zone of that fossil ; 

 while the lowest fossiliferous horizon of this locality seems, from the 



