1882 .] 
325 
[Davia. 
reviewed : it will be noticed that their lakes are now greatly dimin- 
ished in size or altogether evaporated, although the basin remains. 
The plateau of Mexico contains several 1 ; the interior of the 
Argentine Republic, 2 more ; the Kalahari Desert in South Africa 
retains Lake Ngami besides many small pools and dry salt-pans. 3 
Lake Tchad, 4 on the northern side of Soudan near the Sahara, is 
presumably held in a basin of this kind. In Asia there are two 
important Great Basin regions ; the Aralo-Caspian depression on 
the west, once connected with the Black Sea and the Arctic 
Ocean, and the deserts farther east between the northern and 
southern mountain systems. 5 Persia shows the remains of several 
similar lakes, now dried up. 6 
In most of these regions no single lake can claim to be the 
chief or sole descendant of the old occupant ; many small, scat- 
tered pools often remain to share the ancestry, and these will be 
considered under New Land Basins (see below, C. 12) ; perhaps 
some of the examples given should be transferred to that species. 
If we now suppose the disturbed areas which form the rim of 
the Great Basins to approach nearer one another, and the included 
region to take part in their motion as it diminishes in size, we 
shall have — 
A. 2. Mountain Trough Basins. Although this species is 
connected with the preceding by insensible grades, the types at 
the extremes of the series are very distinct. Instead of broad and 
comparatively thin sheets of water, we have now rather narrow, 
trough-shaped lakes, with well-marked banks rising into mountain 
ridges, to which the axis of the lake is distinctly parallel. As a 
rule these basins are full to overflow, their supply being plenti- 
1 Humboldt, Essai politique sur la Nouvelle Espagne, 1811, i, 44. 
2 Peterman, Geogr. Mitt. Erganz’h. 39, 1875. M. de Moussy, Confederation Argen- 
tine, 1860, i, 171. 
3 Livingston, Missionary Travels and Researches in S. Africa, 1858, 72, 75. 
4 Nachtigal, Roy. Geogr. Soc. Journ. xlvi, *1876, 396. 
3 Richthofen, China, I, 103 and pi. 2. Prejevalski, From Kulj a across the Tian Shan 
to Lob Nor (trans. by Morgan), 1879. 
6 Blanford, Geol. Soc. Journ., xxix, 1873. 493. Geogr. Soc. Proc. in, 1881,79. Tietze 
suggests that some of the Persian plains have been formed by wind action and not as 
lake-beds. Wien, Jahrb. Geol., xxvn, 1877, 341. 
