1 66 Transactions of tJie [Sess. 



11. Cornaceae. — This small order, the last we will notice at present, 

 is distinguished for the astringent properties of the bark. The nine 

 genera and forty species comprised in it are found in the temperate 

 zones of both hemispheres. The specimen exhibited is Cornus florida, 

 or the Flowering Dogwood. It is a tree from twenty to thirty feet 

 in height. The bark is exactly similar to Peruvian bark in its pro- 

 perties as a tonic. "The true flowers are inconspicuous, greenish- 

 yellow, but the involucre is very large and showy, of veiny, white, 

 obovate leaves, ending in a callous point, which is turned up or down 

 so abruptly as to appear eniarginate." The wood is extremely hard, 

 and very durable. 



XII.— NOTE ON THE WESTWARD MIGRATION OF THE 

 FLORA AND REPTILIAN FAUNA OF THE EURO- 

 PEAN CONTINENT, AS EVIDENCED ON THE MAIN- 

 LAND OF SCOTLAND, SOME OF THE SOUTHERN 

 HEBRIDES, AND IRELAND. 



By Mr SYMINGTON GRIEVE. 



(Bead March 27, 1884.) 



It is now generally admitted that, during the last glacial period or ice age, 

 there was a very general depression of the land in the northern hemi- 

 sphere. This depression, it is believed, was caused by the tremendous 

 ice-cap that covered this part of the world, the enormous weight caus- 

 ing a displacement of the earth's centre of gravity, and also altering 

 the position of sea and land by causing the sea to rise much above its 

 present level. On the strong grip of the ice age being relaxed, there 

 is supposed to have been a gradual upheaval, until Eritain and the 

 adjoining islands were no longer insular, but formed part of the 

 European continent. By the time that Britain had become conti- 

 nental, very probably the ice had melted from the lowlands, and had 

 receded some distance up our mountain-sides, and the climate had 

 become sufficiently temperate to admit of the existence of those plants 

 that we now find at the summits of our highest peaks, and which we 

 caU " arctic alpines," a few of which we still meet with at the sea- 

 level — the stragglers that were left behind by the migrating army of 

 arctic alpines on their omvard march. But we must not suppose that 

 those stragglers fell out of the ranks from being too weak to continue 

 their travels : it was the cii'cumstance that they met on our shores 

 with congenial conditions of climate and soil, combined with freedom 



