General Notes. 

 i the sphenoid is much hi<: 



the fold of tl 



le palatine is vertic; 



il. 









Origin of 



the Prairies.— I i 



lotici 



: in 



the Ami 



BRICAN NATUR- 



a list for May a note on" The 



orig 



in of 



" the pra 



iries," in which 



the Indian ci 



istom of burning th 



' U r '-<i 





. made t 



o play a major 



part. Now, 



it seems to me, that this 



!I1,|V 



help to 



account for the 



slow spreadit 



ig of forests, but n< 



Dt fo 



r tin 





of the prairies 



Why did not 



trees spring up ove 





: p it- 



t of the . 



country as well 



as another? 



This is the questi 









not the forests 



spread ? A 



reason often given i 



s that th< 



i forests 



nourished only 





is because the praii 









but the timber 



often covers 



the highest points 



and 



is n 



lot fount 



1 on the lower 



Did not the native grasses cover the ground first and thus pre- 

 vent all light seeds from finding a place to grow? and as only the 

 light seeds would be transported by the wind, and thus spread 

 rapidly, the extension of the tree-covered areas was very slow. 



We observed several years since, that in Northern Ohio trees 

 of the genus Populus, other than' P. trcmuloides, were very rare. 

 Now they are not uncommon. Wherever a brushpile was burned 

 at the proper season, if it was not a period of drought, the cotton- 

 wood appeared. The seeds must have come with the winds, and 

 wherever they found soft earth ready to receive them, if the sea- 

 son was favorable, they grew. Of course the oak, hickory, wal- 

 nut and beech could not travel in this way.' 



It seems to me that in these facts we have an important element 

 of the solution of this much-debated question.— J. IV. Hitett, 

 Ottawa, III. 



Davis' Classification* of Lake Basins.— This is a valuable 

 essay, by Mr. W. M. Davis, on a topic in physical geology which 

 has not before received such detailed and special treatment. It is 

 reprinted from the Proceedings of the Boston Society of Natural 

 History (Vol. xxi, [882). The author's primary classification of 

 lakes is into three classes: A. Construction or orographic basins, 

 of which U) great basins such as Great Salt lake and the great 

 lakes of Cental Africa are examples, (2) mountain trough basins 

 (the western part of Lake Superior), (3) fault basins (the Dead 

 sea and other species); B. Destruction or erosion basins, of 

 these are the following species: (1) Glacial erosion basins, \ 2) 

 wind erosion, (3) solution. (4) pit crater basins ; and C. Obstruc- 

 tion, barrier or enclosure basins, of which the most important are 

 ([) fan delta barrier basins, (2) ice barriers, (3) moraine barrier 

 basins. (4) drift barrier basins and a number of other species. 



The author claims that the Great lakes, the Italian and other 

 lakes, regarded by Ramsay, Logan, Newberry and others as due 

 to glacial erosion, are more properly examples of what he ca.ls 

 "drift barrier basins." He considers that besides, the small 



