TRIASSIC SYSTEM. 
65 
ctis, and the Meekoceras zone with the zone of Prionolohus rotundatiis 
and Celtites sp. With regard to the Meekoceras zone, Dr. von Krafft 
stated, in the paper quoted above, that it certainly 
Meekoceras zone. belonged to the lower trias, while he left the age 
of the Ophiceras zone doubtful, having no proof of either a permian or 
a triassic age. On the other hand, Dr. Noetling has correlated the 
latter zone with the uppermost permian, on account of the supposed 
absence of the genus Meekoceras ^ ; but, as will be seen from the list 
of fossils already given, that genus has been found in the Ophiceras 
zone in Spiti, and any attempt at correlation on this ground with 
the zones of Medlicottia wynnei and Euphemus indicus therefore 
fails. 
It would perhaps seem unnecessary to discuss this question in such 
detail in the present memoir, but it has been deemed advisable to indi- 
cate as briefly as possible the present state of the discussion^ which may 
be summed up as follows : — 
The Meekoceras zone has been unanimously referred to the lower 
trias: the age of the Ophiceras zone was looked upon as doubtful by 
Dr. von KrafTt, while the reason given by Dr. Noetling for placing it 
in the permian system is not valid for Spiti ; with regard to the 
Otoceras zone, a strong case in favour of its permian age has been made 
out by Dr. von Krafft in the supposed identity of M edlicottia wynnei, 
Waagen, with M. dalailams^ Diener. This question of identity or 
otherwise can be decided only by specialists, and as it still remains 
a matter of dispute, it has seemed preferable in the present memoir to 
describe the zone in connexion with the series to which it belongs 
litholootcally, leaving its age an open question. As already stated, it 
was regarded by Mr. Griesbach as a passage-bed between the permian 
and trias, and until many more sections in the Himalayas have been 
.vorked out in detail, it is unlikely that we shall be able to assign it 
definitely to one system or the other. 
Above the Meekoceras zone there is an alternating serie of thin- 
' Op, at., p. 466. 
( 65 ; 
