rOPT?KLATTON OF TITK LOAVEU TRIAS. 
33 
agrees entirely with that of Spiti and is also contained in a concretion- 
ary limestone of dark blue colour. 
The direct superposition of the Meekoceras horizon above the 
Ophiceras bed in Spiti has often rendered an exact separation oi their 
faunae in situ very difficult or even impossible. They are certainly 
linked together by a number of species common to both of them 
Neither is Meekoceras entirely absent in the lower horizon nor Ophiceras 
in the upper one. In Spiti Meekoceras Varaha and M. lilangense are 
the commonest species, whereas in Painkhanda M. Markhami predo- 
minates. In Spiti the Otoceras stage is poor in species, compared with 
the rich fauna of the Otoceras beds in Painkhanda, but the Meekoceras 
fauna is more richly developed in the Spiti sections. 
Throughout the upper division of the Lower Trias in Painkhanda 
and Spiti a single and uniform fauna only has been found. This is the 
fauna of the Hedenstroemia beds or the zone of Flemingites Rohilla. It 
differs considerably from that of the Meekoceras beds. The genus 
Meekoceras is chiefly represented by large species belonging to the sub- 
genera Aspidifes and Koninckifes. Xenodiscus, Flemingites and Heden- 
stroemia have reached their maximal development 
In the topmost beds of the Hedenstrcemia stage of Spiti a bivalve 
facies, with Pseudomonotis hmaica Bittn. as leading fossil, makes its 
appearance, but the stratigraphical independence of this bivalve lime- 
stone as a distinctly marked palseontological horizon is very doubtful. 
The fourth and youngest fauna of Lower Triassic age is hitherto 
known from one locality in Byans only. 
A small faunula collected by F. H. Smith near Jolinka has been attri- 
buted by A. V. KrafTt to a stratigraphically well defined bed, not far 
from the top of the chocolate limestone. It represents the zone of 
Sihirites spiniger and consists exclusively of species of the genus 
Sibirites, which is restricted to the upper Ceratite limestone of the Salt 
Range. 
Sibirites spitiensis in the section of Muth is perhaps indicative of a 
representation of this palseontological zone in the Hedenstroemia beds 
of Spiti. 
g. Correlation with the Ceratite beds of the Salt Range. 
A large area of Lower Triassic sediments is exhibited in the Ceratite 
beds of the Salt Range. Here, as in the Himalayas, the most 
D ( 234 ) 
