1897.] NATURAL SCIENCES OF PHILADELPHIA. 425 



The following is a free rendering of M. Karpinsky's general de- 

 scription (L. G. V.) : In the most important rivers of the east slope 

 of the Oural, such as the Toura, Taguil, Nitza, Irbit, Pychma, Isset, 

 Sinara, Tetch, Miass, Ouwelka, Oui and Togonzak, the lower course 

 is the most extended. Their western limit coincides almost with 

 the western limit of the region occupied by the tertiary deposits. 

 (See the geological map of the eastern slope of the Oural.) The middle 

 course of these rivers is generally the shortest. The rivers of the 

 Asiatic system of the Ourals are also less abundant in water than 

 those of the European system. The vast lake system of western 

 Asia along the Ourals extends from the very mountain region itself 

 down to the axis of the divide (as in the case of Lake Itkoul, etc.). 



In proportion to the distance from the Oural chain the character 

 of the lakes changes more and more, and several types united by 

 those of intermediate character can be recognized. Between the 

 ramifications of the Ourals and near the boundary between the moun- 

 tain and plain of the east slope, lakes which form on their borders 

 islands and rocky promontories in greater or less number are found 

 scattered far apart in a region constituted essentially by crystalline 

 rocks. Their contours, predominant directions, and distribution, 

 depend habitually on the direction of the schistose crystalline rocks 

 forming the region. In this same direction strings of lakes are 

 found ordinarily enclosed in a belt formed by the same rocks (see 

 on map lakes Silatch, Soungoul, Kerety, Kasli, Irtiach and Bol- 

 chaia-Nanoga, Miassowo, Terenkoul, little and great Kissiagath, 

 Yelowoie and Tschebarkoul). All these lakes have considerable 

 depth even near their shores. Most of them have visible outflows, 

 and their water is always fresh. The lakes of the steppe remote 

 from the Ourals have an entirely different character. Their number 

 is very great, as is the space over which they are distributed, which 

 extends far to the east. 



These latter lakes are found in a region occupied by horizontally 

 stratified tertiary deposits. Their forms are simple, and in spite of 

 their large dimensions they are ordinarily shallow. Near their 

 margins one often sees terraces of rounded forms, a proof that at one 

 time they occupied larger spaces. Regularity is observable neither 

 in the directions of their greatest elongation nor in their grouping. 

 Almost all of these are without efflux. Many of them contain fresh 

 water, though in others the water is saline, and in a part of them 

 salts have been deposited. The salt is predominantly NaCl with 



