CARBONIFEROUS SYSTEM. 3g 
Discina sp. 
Conocardtum sp. 
Aviculopecten sp. 
Platyceras sp. 
Pleurotomarta sp. 
Phillipsia cf. cltffordi, Woodw. 
Helodus crenulatus, Newberry and Wortheii. 
Polypora sp. and numerous crinoids. 
With these occur numerous specimens of Orthotetes sp. or Derhyia 
sp., resembling D. senilis, Phill., but the internal characters cannot be 
distinguished, and it is consequently impossible to refer them definitely 
to either genus. 
There can be no doubt that the age of the beds in which the above 
fossils occur is carboniferous, and though some of the forms are 
common to the whole of that system, yet, from the presence of 
Syringothyris cuspidata, Phillipsia cf. cltffordi and Helodus crenw 
latus, it seems probable that the limestone is of lower carboniferous 
age. The same horizon has been recognised at Muth and Kuling 
in the Pin valley and Tr5kse, near the head of the Spiti river. 
Horizon {b). — This is a band of shale, 3^ feet in thickness, which 
occurs at about 117 feet above the top of the white quartzite (No. 5). 
The fossils, though numerous, are much crushed and are often 
merely casts or impressions ; they consist chiefly of large numbers of— 
Spirifer f.p. • 
Discina nttida, Phiil. 
„ cf. nevoberryi, Hali. 
Lingula cf. mytiloides. Sow. 
Pleurotomarta sp. 
Ret eta sp. 
Horizon [c). — About six feet higher up another band of shale 
contains impressions of — 
Spirifer sp. 
Rhynchonella pletirodon, PhiW. 
Aviculopecten sp. 
Orthoceras sp. 
The spirifer and Rhynchonella are very common. 
H orison ((^).— This horizon consists of a highly fossiliferous bacd 
( 39 ) 
