78 
HAYDEN: GEOLOGY OF SPITI. 
allied to, Halobia comata, Bittner, and H. fascigera, Bittner, it has 
been considered advisable to separate the Halobia beds as a distinct 
subdivision. 
This limestone is overlain by a thick series of soft, grey or pale 
lavender shales with which thin bands of lime- 
Grey beds. 
stone are mtercalated. Almost immediately above 
the Halobia limestone, the shales contain a band of black concretions 
which enclose numerous ammonites ; the fossils are in most cases 
fragmentary, and only one species has been completely determined : 
this is 
yoannites cymbiformis, Wulf., 
which has been found at this horizon at several localities, in Spiti and 
also in the Thanam valley in Bf>shahr, The remaining fossils include — 
Trachyceras cf. aonoides, Mojs. 
„ n. sp. aff. arice, Mojs. 
Hauerites n. sp. 
Drepanites n. sp. 
Joannites cf. cymbiformis, Mojs. 
Only one other fossiliferous horizon has been found in the grey shales; 
it occurs at about 300 feet above the base, and consists of a grey, shaly 
limestone, containing large numbers of brachiopods, which include — 
Spiriferina shalshalensis, Bittner ; 
Rhynchonella lankana, Bittner ; 
Discina sp. ; 
and several other forms not yet determined. One ammonite [Disti- 
chites sp ) was found by Dr. von Krafft in this bed, while Megalodon 
sp. and other bivalves occur in the upper part of the series. 
The brachiopod horizon is overlain by grey shales, about 200 feet 
thick, similar to those below : thin bands of limestone are intercalated 
with the shales and become more and more numerous in the upper part 
of the series, till the formation becomes one of limestone, with subordi- 
nate bands of shale : this is subdivision (3) in the above list. Fossils 
Brachiopod lime- are rare, but above Muth and near Lilang the 
limestone contains at one horizon large numbers 
of brachiopods and bivalves, which, however, still await determination, 
( 78 ) 
