152 THE JOURNAL OF INDIAN BOTANY. 



in the fact that the latter part is much more open. The initial level 

 of the valley is of course higher in Lahoul than in Pangi. 



There are absolutely no Liverworts beyond the Inner range. Of 

 the other cryptogams only one alga which looked like a spirogyra 

 was seen. No fungus, but two or three lichens were observed. One 

 or two species of mosses were noted near running water. Only a 

 single fern plant was seen but unfortunately was not identified. The 

 flowering plants of this interesting region would be dealth with at a 

 later date. It may perhaps be mentoined by the way that red snow 

 due to the unicellular alga Chlaydomonas'jiivalis was observed just 

 below the Baralacha pass on the south side at about 16,000 ft. 



The facts of vertical distribution on the southern slopes of the 

 Outer Himalayas can readily be explained by the increase in the rain- 

 fall with the increase in height up to a certain limit after which the 

 very low temperature acts as an adverse factor. 



One interesting result as regards vertical distribution is that 

 both the highest and the lowest genera of the Marchantiales are 

 met with at the highest and the lowest levels. The lowest genus 

 Eiccia is represented by B. robusta at Lahore (700 ft.) and at 

 Lahoul (11,000 ft.). Of the highest genus Marcharitia, M. nepahnsis 

 and M. palmata are very common in the plains and the outer Hima- 

 layas up to about 7,000 ft., while 1/. polymorplia goes up to about 

 11,000 ft. in the Chandrabhaga valley. Another genus, Grimoldia, 

 about midway between the lowest and the highest genera is also 

 widely distributed in this region. The only Indian species, G. in- 

 dica, is very common from the foot of the Himalayas to about 

 11,000 it 



The horizontal distribution is not so easy to explain. That the 

 rainfall is not an essential factor is shown by the fact that it does not 

 differ very much in the different places where collections have been 

 made. Probably temperature connected with a higher latitude has 

 something to do with it. The problem requires more study. 



In the Ravi valley the rainfall is not a very important factor as 

 it is not very high and isaccompanied by a comparatively low temper- 

 ature, and Liverworts are thus generally met with only near 

 permanently moist places. A few occur otherwise. 



In the Beas valley (Kulu) although the rainfall is not very high 

 but the broad valley is surrounded by hills on all sides and at higher 

 levels there is a luxuriant Liverwort flora which compares very well 

 as regards the number of species and individuals with localities 

 further to the east. 



In the Chandrabhaga valley rainfall does not count as a factor 

 at all in the distribution of Liverworts. It is very small and therefore 



