IV. EXPLANATIONS. 351 



At or above 1400 yards, 12 species in Mid Scotland. 



The plants which find an upper limit between 250 and 350 yards in 

 Mid Scotland, are less fully ascertained. But after making some addi- 

 tions on this account, those of Scotland would not count to an equality 

 with those of England below 300 yards ; although more numerous above 

 that height. 



3. Upper limits elsewhere. — Little explanation can be needed in 

 regard to this short list. Tt is supplementary to the two preceding 

 lists ; including a few plants not noted in them, or noted only at lower 

 altitudes, or the stated heights of which it seemed desirable to corrobo- 

 rate by their position elsewhere. Sedtim anglicum and Scilla verna 

 exemplify the first ; — Hymenophyllum Wilsoni and Vlex europceus, the 

 second -y—Arhulus alpina and Ilex Aquifolium, the third. 



It is much to be wished that some competent observer of such things 

 would carefully trace out the altitudes of plants in Wales. Very little 

 has yet been attempted there, and only at a season quite unsuitable for 

 mountain botany. But in every or any part of Britain a careful repeti- 

 tion or re-examination is also desirable. The chief object now should 

 be to carry forward observations on the altitudes of plants into more 

 exact details, and with increased accuracy, throughout Britain. In first 

 attempts there must always and unavoidably be great sacrifice of time 

 in proportion to the results attained ; the progress being very slow com- 

 paratively with that which may subsequently be achieved. For instance, 

 both absolute and relative heights of the species are so imperfectly 

 known by casual observation, as to be virtually unknown for purposes 



