ERRATA. 



Page 124, for Track No. IV. read No. V., and for Track No. V. read No. IV. ; 

 these numbers and their paragraphs should have been thus transposed, in order 

 to agree with the map. — P. 126, 1. 13 fr. top, after appears, insert not. — P. 128, 1. 2' 

 fr. bot. for basis, read basin. — In the note, p. 129, 1. 6 fr. bot. after by, insert th^ 

 displacement of. 



