MEETING OF THE BRITISH ASSOCIATION. 49 
competent than myself the task of drawing conclusions therefrom, and 
ol instituting comparisons with other observations in different parts of 
Europe. 
The district from whence I have obtained those facts maybe roughly 
described as extending from Mentone along the seacoast nearly to 
Bordighera, about ten miles W. to E., and thence some forty miles N 
to the great watershed of the Maritime Alps. 
The general course of the chief rivers is from N. to 8., but there are 
many tributary streams which run substantially E. and W. It will 
thus be apparent that this district presents every variety of aspect. 
The great forests are on the northern slopes, where they have more 
of moisture and less of sun than on the other aspects. 
Of this tract the two-thirds nearest to the sea are mainly composed 
of Jurassic limestone, but include nearly everything from thence up to 
the most modern strata. Altered rocks and porphvry occur exten- 
sively in the northern third. 
The range of the thermometer at different elevations is great. The 
winter of 1864-65 was severe; and while the lowest degree registered 
m the shade to the N. of my house at 36 min. above the sea was 30 
deg. F., the instrument on the Gnmmondo, at an elevation of 45 deg. 
25 min., went down to 10 deg.,* and this at a distance of less than 
seven miles in a direct line. 
One fact somewhat bearing upon my subject may be mentioned, 
gregarious until we arrive 
Conift 
and P. halepensis rarely intermingle. The species occurring in the 
colder regions do intermingle, as A. Larix and P. st/hestris. Another 
observation, not perhaps quite so cognate, I may be allowed to men- 
tion, viz. the great sensitiveness of P. halepensis. When the morning 
»s warm and sunny, its leaves are fully expanded ; if the sky becomes 
overcast, they close partially ; the sirocco produces a similar'but more 
marked effect ; but in rain the leaves are completely closed, giving the 
tree a mos t melancholy aspect. 
The limits assigned in the following table indicate the heights above 
J e sea at which the several species occur, and cease to appear in any 
Febr the greatest cold of that wint er, occurred between March 17th and 
e ruary 10th, up to which time the lowest marked was 14 deg. The thermo- 
meters had been carefully compared. 
VOL. V. [FEBRUARY I, 1867.] E 
