i6 
HAYDEN : GEOLOGY OF SPITI. 
The next horizon from which fossils have been obtained in any 
appreciable number is bed No. 2 (" dark slate with trilobites "). In 
this bed and in No. 4, numerous remains (chiefly head-shields) of trilo- 
bites occur ; they are unfortunately all poorly preserved. 
Bed No. 6 has yielded a large number of specimens, many of which 
are in a very fair state of preservation ; they consist chiefly of species 
of Ptychopan'a, Corda and allied genera. 
In bed No. 9, Ptychoparia is still found, and with it large numbers 
of fragments of Olenus sp., and Dihelocephalus sp. 
The highest zone in which determinable fossils have been found is 
bed No. 13: they are, however, not numerous. Ptychopafia \s very 
rare, being almost entirely replaced by species of Olenus. 
Collections were made from all the above horizons, but have been 
sent to England for description. It is therefore at present only pos- 
sible to give the above generic determinations, founded on a cursory 
examination made by the present writer before the despatch of the 
materials to England. These data, though meagre, are yet sufficient 
to warrant the inference that the fossiliferous beds are of upper — pos- 
sibly also of middle — cambrian age. 
As already stated, the series attains its greatest development in 
the valley of the Parahio, where its total thickness is nearly 1,200 
feet. In the section described, the uppermost dolomite has under- 
gone considerable alteration and contains no determinable fossils, 
though a few fragments of head-shields of trilobites have been 
found in it, but the lithological continuity of the series up to the 
base of the conglomerate (19) renders it desirable, in the absence 
of proof to the contrary, to place the whole in one and the same 
system. In addition to this, a distinct change in the character of 
Unconformity above the deposits, accompanied by a marked uncon- 
the trilobite beds. formity, occurs at the base of the conglomerate, 
and in view of the not infrequent coincidence of a palaeontological with 
a lithological break, the upper quartzites, slates and dolomites have 
been included with the underlying fossiliferous beds, in the upper 
( 16 ) 
