IlfMALWAN FACIES: SHMMAKY. 
1-27 
general outlines, whereas from Kashmir and Ladakh only isolated data 
are as yet available. 
1. Lower Trias and Muschelkalk are developed almost equally well 
in Spiti on the one hand and in Painkhanda on the other. The lower 
Trias contains at least three separate fauna?, namely, the Otoceras-Ophi- 
ccras fauna, the Meekoceras fauna, and the Flemingites-Heclensfrmnia 
fauna. To this must be added the Sihirites fauna, which is hitherto 
known with certainty from Byans only. Subdivisions of the Lower 
Trias must therefore be based on those clearly marked palfeontological 
horizons. The former subdivision into Otoceras beds and Subrobustus 
beds must be abandoned, since the genus Otoceras is confined to a thin 
layer at the base of the lower Trias, while Ceraliles subrobustus 
( = Kei/serlingites Dieneri Mojs.) belongs exclusively to the Lower 
Muschelkalk. 
The Muschelkalk naturally falls into three subdivisions. The lower 
division consists of a nodular limestone poor in fossils, wliich is under- 
laid by a brachiopod- bearing layer with BhynchmcUa Griesbdchi . The 
middle division (zone of Spirijerinc Hirnclieyi) contains the fauna of 
Keyserlingites Dieneri {Ceratites subrobust us antea). The Upper Mus- 
chelkalk is very rich in cephalopods and represents, indeed, the richest 
and most widely spread fossil horizon of the Himalayas. 
In Byans Lower Trias and Muschelkalk show a development different 
to that found in the other districts. The Muschelkalk consists of a 
much purer limestone facies than is the case to the north-west of that 
district. Faunistically, however. Lower Trias and Muschelkalk of 
Byans do not dif?er considerably from the equivalent beds of Spiti and 
Painkhanda. The topmost beds of Lower Triassic age contain the fauna 
of Sibirites- sj.ini'jer which is probably homotaxial with that of the 
Upper Ceratite limestone in the Salt Range. 
2. A strongly marked difference in thickness and lithological charac- 
ter sets in in the ladinic stage. While this stage is rich in fossils and of 
considerable thickness in Spiti, it is thin and poor in fossils in Pain- 
khanda. Further to the east the ladinic stag^ has not yet been traced. 
3. The marked difference just referred to is equally prominent in the 
carnic deposits. These are rich in shaly beds and very thick in Spiti, 
but dwindle considerably towards the east till in Byans their thickness 
is almost insignificant. At the same time the shales disappear and their 
place is taken by pure limestones. 
( a-28 ) 
