ANNOTATIONS AND ADDITIONS. 89 



catepetl in Mexico, and only 92, 104, and 156 geogra- 

 phical miles in those of the South American volcanoes Sangai, 

 Tolima, and de la Fragua, respectively. I exclude from 

 these statements all extinct volcanoes, and all trachytic moun- 

 tains which have no permanent connection with the interior of 

 the earth. (Asie Ceutrale, T. ii. p. 16-55, 69-77, and 341- 

 356.) East of the volcano of Turfan, and of the fertile 

 Oasis of Kami rich in fine fruit, the chain of the Thian- 

 schan gives place to the great elevated tract of Gobi which 

 follows a S.W. and N.E. direction. This interruption of 

 the mountain chain, caused by the transverse intersection of 

 the Gobi, continues for more than 9|- degrees of longitude ; 

 but beyond it the mountains recommence in the somewhat 

 more southerly chain of the In-schan, or the Silver Moun- 

 tains, running (north of the Pe-tscheli) from west to east 

 almost to the shores of the Pacific near Pekin, and forming 

 a continuation of the Thian-schan. As "I have viewed the 

 In-schan as an easterly prolongation (beyond the interruption 

 of the Gobi) of the cleft above which the Thian-schan stands,so 

 one might possibly view the Caucasus as a westerly prolonga- 

 tion of the same, beyond the great basin of the Aral and Caspian 

 Seas or the depression of Turan. The mean parallel of latitude 

 or axis of elevation of the Thian-schan oscillates between 

 40-1 and 43 N. lat. ; that of the Caucasus, according to 

 the- map of the Russian Etat-Major (running rather E.S.E. 

 and W.N.W.), is between 41 and 44 N. lat. (Baron von 

 Meyendorff, in the Bulletin de la Societe geologique de 

 France, T. ix. 1837-1838, p. 230.) Of the four parallel 

 chains which traverse Asia from east to west, the Thian- 



