446 NATURAL SCIENCE. august. 



beds of the Himalaya and the Alpine regions. As there is a 

 complete passage upwards from the Permian, there are probably 

 represented some strata not found in localities where there is evidence 

 of a break between Permian and Bunter. 



The Rhsetic beds comprise a great thickness of dolomites and 

 limestones, characterised by Lithodendron and Megalodon in the lower 

 beds, and with Crinoid-limestones and Brachiopods of Upper Kossen 

 facies in the higher portion. Strata regarded as Passage-beds 

 between the Rhsetic formation and the Lias, yield Pecten valoniensis, 

 Cavduim rh^ticum, some Liassic Limas, and other fossils. The thick- 

 ness of the Rhaetic formation is upwards of 2,000 feet ; and the beds 

 are surmounted by black shales and dark earthy limestones, with 

 oolitic structure altogether about 100 feet thick. These beds are 

 assigned to the Lias; and they contain Ammonites annulatus, Bekfnnites, 

 Gervillia, &c. 



Some confusion is caused by the employment of the term 

 Jurassic in the sense in which Oolitic series is used in this country, 

 so as to exclude the Lias; a grouping that is not according to general 

 custom. 



The beds that succeed the Lias are the Spiti shales, so named 

 by Stoliczka ; they attain a thickness of 1,300 feet, and embrace the 

 entire series of deposits between the Liassic strata and the grey and 

 greenish sandstones that are assigned to the Lower Cretaceous system. 

 From these Spiti beds, which are, perhaps, the best known and most 

 widely-distributed of the Himalayan formations, numerous fossils 

 have been collected, not only by geologists and travellers, but by 

 natives of Tibet and India. The author tells us that from ancient 

 times a trade in the Ammonites has existed ; great quantities of them 

 being brought every year to India, chieily to the holy places of Hindu 

 pilgrimage, to be sold as relics to the worshippers. 



Although no unconformity can be traced in the stratification of 

 the Lias and the Spiti shales, there is an alteration in lithological 

 character, accompanied by a sudden change in fauna. There is, 

 apparently, an absence of the Lower Oolitic fauna (Lower Jurassic 

 of the author), but the lowest portion of the Spiti formation has 

 yielded no fossils. Higher up there are found Ammonites of 

 Oxfordian type ; and the upper Spiti shales are of Tithonian age. 



The Spiti shales are much affected by the grand flexures ; they 

 have frequently been squeezed into the narrowest folds, while the 

 rigid Cretaceous strata have been pushed over them. 



The Spiti beds pass gradually into strata that are grouped as 

 Lower Cretaceous or Neocomian, and the same succession is found 

 to occur through the northern part of Persia and along the shores 

 of the Caspian. These "Lower Cretaceous" beds, 1,200 to 1,500 

 feet thick, consist mostly of sandstones and shales. They yield a few 

 crushed Belemnites, and it is just possible they may be of Upper Titho- 

 nian rather than of Lower Cretaceous age. They are overlaid by 



