88 W. T. Blanford— On the Physical Geography [No. 2.. 



Rhinoptihcs, the family Gyclostomidae, &c. With many of these the genera 

 are different in India and Africa, though less frequently than in the first case, 

 or, which is more to the purpose (for genera are often artificial, and depend 

 upon human fancy quite as much as natural laws) , the amount of divergence 

 is less. The third group comprises forms which are found in Northern Africa 

 Arabia, Persia, and India, but which do not extend to the Malay countries, 

 such as Hyaena striata, Cams aureus, Felis leo, F. jubata, F. chaus, Gazella, 

 Gerbillus, Pterocles, Pyrrhwlauda, Gursorius, Saxicola, &c. In this case 

 the genera and very often the species are identical. Many of the forms are 

 also found in the neighbouring portions of the boreal or palsearctic region, and 

 their number diminishes in India itself to the eastward and southward, 

 whilst but few are found in forest. The forms belonging to this category 

 appear to be recent immigrants. 



§ 3. The Indo-gangetic Plain between India and the adjoining regions 

 of Asia. — Thus both from geological and zoological evidence we have reason 

 to conclude that the union of the Indian Peninsula with Central and 

 South-western Asia is of comparatively late date, and it becomes a question of 

 great interest to ascertain so far as possible the evidence of their own condi- 

 tion in the later geological epochs afforded by the tracts of flat country 

 intervening between the peninsular area and the surrounding regions. 

 These tracts consist chiefly of the great plains through which the Ganges 

 and Indus flow to the sea, and the surface is covered to so great a depth 

 by alluvial deposits from those rivers and their tributaries that very few 

 traces can be found of the geological history of the country. It has been 

 assumed by some writers that this great plain remained part of the 

 sea long after the Himalayas had been elevated. This is not impossible, 

 but so far as the Gangetic area is concerned I fail to see that there is evi- 

 dence in favour of the view ; and I think the idea is mainly due to the 

 Pliocene Sevalik deposits having frequently been considered marine, whilst 

 it is more probable that they are really of freshwater and probably subae- 

 rial origin, for not a single marine organism has been detected in them, 

 whilst freshwater shells have been found in them in places. Even without 

 entering into the question as to whether the whole Indo-gangetic plain has 

 been covered by the sea in late geological times, the question arises whe- 

 ther the Indus plain, in which we have the latest evidence of marine life, 

 has been thus covered. This is a speculation of Mr. Andrew Murray, 

 proposed to account for the presence of a dolphin in the Indus and Ganges, 

 and for the difference of the species inhabiting each.* 



* Geographical Distribution of Mammals, p. 214. Mr. Murray's theory is briefly 

 the following. The dolphin inhabited an arm of the sea which became a lake 

 through the rise of land, and which was gradually rendered fresh by streams falling into 

 it and cutting their way to the sea, first in the direction of the Ganges, secondly through 



