SILURIAN SYStEM. ^5 
The only fossils found in the lowest bed (No. i) were impressions of 
Orthis sp. ind., plant remains, including Bulhotrephis sp, cf. gracilis, 
Hall, and crinoid stems. 
The overlying limestone (No. 2) contains numerous fossils, chiefly 
trilobites and brachiopods, the latter belonging 
Trilobite limestones. , ^, ^7 i.i 
to the genus Strophomena ; the commonest 
forms are— 
Chtirurus cf. obtusatus, Cord, 
„ sp. 
Illesnus punctulosus. Salt. 
„ sp. 
Asaphus cf, emodi, Salt., and other species, 
Calymene cf . nivalis, Salt. 
(?) Bronieus sp, 
Strophomena cf. alternata. Sow, 
„ chamerops, Salt. 
„ trachealis, Salt. 
„ cf. lineatissima, Salt. 
Leptcena sericea, Sow. 
Orthis, sp. 
Tentaculites, sp. 
Stromatopora concentrica, Goldf. 
Several of the above forms are characteristically lower silurian, and 
the limestone is probably of Caradoc age. It will be noticed that some 
of the species have been identified with forms collected by .Strachey in 
Niti ^ and described by Salter.* There is, indeed, little room for doubt 
that the series of limestones, shales and marls between the lower 
silurian red quartzite and the white (Muth) quartzite of Spiti is the 
western continuation of the beds from which Strachey's collections 
were obtained. 
Above the trilobite limestone is a band of hard, grey and brown 
limestone (3), about 30 feet thick, which contains brachiopods in the 
lower layers, and Cysttdea in the upper. The brachiopods appear to 
belong chiefly to Orthis flabellulum, Sow., with which are associated 
Atrypa hemiplicata, Hall, and corals, chiefly species of Favosites. 
•Quart. Journ. Geol, Soc., vol. VII (1851), p. 303. 
•Palaeontology of Niti. 
( ^5 ) 
