50 
HAYDEN : GEOLOGY OF SPITI. 
Above Lanjarse there is a fairly complete section of the beds 
overlying the Fenestella shales, but no trace of the band of fossiliferous- 
concretions was found, and it is therefore probable that at Po these two 
horizons are in their true positions relatively to one another. This 
could not be ascertained definitely at Lanjarse, for the Fenestella shales, 
underlain by a bed of quartzite, form the base of the section. It is 
probable, however, that the two horizons are not separated from one 
another by more than a small thickness of rock, for the same species 
of Bryozoa are numerous in both, and they should perhaps be grouped 
together as one horizon ; this can only be determined by a more 
detailed examination of the sections between Po and Thdbo, and 
opposite Thabo, on the right side of the Spiti river ; the latter locality, 
though difficult of access, appears to offer a more continuous section 
and one well adapted to detailed study. 
At Losar, however, near the head of the Spiti river, the Fenes- 
tella shales, which are found in the high hills behind the village, con- 
tain brachiopods (including Productus scabriculus, Mart.) exactly 
resembling those found in the concretionary band near Po. This 
constitutes a further argument in favour of including the latter band 
with the Fenestella shales. 
With regard to the age of these beds the collections obtained are, 
Age of Fenestella '^^ feared, too small to offer conclusive evi- 
shales. dence, but owing to the presence of such large 
numbers of Bryozoa, it was originally suggested by the present writer ^ 
that they might correspond to the Zewan beds ^ of Kashmir. This 
question cannot be decided till the Spiti collections have been worked 
out in detail : for this purpose, they have, as already stated, been sent 
to Professor Diener, who has kindly informed the author that he be- 
lieves the provisional correlation of this horizon with the Zewan 
beds to be correct. Those beds have been regarded by both Waagen 
» General Report, G. S. I., 1899-1900, p. 189. 
* Quart. Journ. Geol. Sec, vol. XXII (1866), p. 29; Journ. As. Soc. 
Beng.rvol. XXXV, p. 128, vol. XXXVI, p. 208; Memoirs, G. S. I., vol. XXII, 
p. 132 ; Indica, ser. XV, vol. I, pt. 2. 
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