CORRELATION OT TIIK MTDDLF, TRIAS. 
83 
which in its external sculpture recalls the Arctic section of Dinarites 
spiniplicali {OlenekUes), whereas in its sutures it agrees with Keyserlin- 
gites Middendorffi Keys. The affinity of tlie Arctic group of Ceralites 
polaru to the Indian subgenus Hollandites is extremely doubtful. 
During the ladinic stage a close kinship still persists between the 
marine faunae of the Himalayan and Mediterranean provinces. The 
Daonella shales of Spiti, which must be taken as prototype of this stage 
in India, have a considerable number of species in common with the 
Wengen beds of Tyrol. Those species are : — • 
Protrachyceras Archelaus Lbe. 
„ longobardicum Mojs. 
„ ladinum Mojs. 
„ c/. regoledanum Mojs. 
Anolcites cf. Laczkoi Dien. 
Hungarites Pradoi D'Arch. 
Joannites cf. Tridentinus Mojs. 
Daonella Lommeli Wissm. 
Out of thirty species of the fauna of the Daonella shales only four 
belong to faunistic elements which are peculiar to the Indian zoo-geogra- 
phical region. One of them i; Ptychites Gerardi Blfd., which together 
with Joannites cf. proavus Dien. ranges from the Upper Muschelkalk into 
the ladinic stage. The second, Thanamites hicuspidatus Dien., belongs 
to a genus which recalls some Palaeozoic ammonites in its very simple 
sutures, among which the narrow and bifid lateral lobe is especially con- 
spicuous. It is a dwarf genus, which probably originated from some 
more specialised type by regressive evolution. Two more species are 
representatives of the genus Rimkinites , which is not known hitherto to 
occur in any extra-Indian territory. 
This proportion of Mediterranean and exclusively Indian elements in 
the ladinic fauna of Spiti is not altered, if the fauna of the passage beds 
connecting the Ptychites limestone of the Upper Muschelkalk and the 
Daonella shales is included. Leaving aside such species as do not exhi- 
bit any affinity with Mediterranean forms, the relationship to Wengen 
species prevails so remarkably, that the fauna of the passage beds must 
also be considered as an equivalent of the zone of Protrachyceras Archel- 
aus (longobardic substage). 
( 284 ) 
G 2 
