CARBONIFEROUS SYSTEM. 41 
Horizon (/). — Forty feet higher up another band of limestone 
contains numerous fossils including — 
Productiis cora, d'Orb. 
Productus semireticulatus, Mart. 
Spirifer sp. 
Athyris royssti, Lev. 
Rhynchonella pleurodon, Phill. 
Urthotetes (?) sp. (or Derbyia sp., resembling Derhyia regularis, 
Waagen). 
Terebratula sp. 
Fish teeth. 
Horizon [g). — The highest horizon in this series at which fossils 
were found is a band of light grey, micaceous shale, 372 feet above 
the white quartzite (No. 5). This bed contains immense numbers of 
Estheria sp. ; they all appear to belong to the same species, which is 
probably new and does not therefore throw any further light on the 
age of the shale. 
It will be seen from the above lists of fossils, imperfect though 
they are, that most of the forms found in the lowest horizon [a) occur 
also at higher horizons, and it is therefore probable that the whole 
series from the top of the white quartzite (No. 5) to the Estheria bed, 
belongs to one and the same subdivision of the carboniferous system, 
while the presence of Syringothyris cuspidata renders it probable 
that that subdivision is the lower. 
The fossiliferous beds pass up into a mass of limestone "about 
500 feet thick, of which the lower beds are hard, dark and flaggy 
while the upper consist of yellow and buff crystalline limestone. In the 
Lipak and Yulang valleys the uppermost beds have been in many 
places converted into a very pure, white gypsum. Similar alteration 
of the carboniferous limestone has taken place at several other localities, 
including Gyumdo E. G. in To-Tzo, HuUng in lower Spiti, the Sumra 
Lei (between Sumra and Sh51kar), Tangi Chenmo in the Gyundi 
valley in upper Spiti, and above Trdkse E. G. near the head of the Spiti 
river. This alteration is not confined to the upper beds, but occurs 
at various horizons in the carboniferous limestones.^ 
* For a fuller description of the gypsum, see below, p. loi. 
( 41 ) 
