128 REVIEWS. 



ing plant." There are only eight or nine phaenogamous 

 species peculiar to the arctic zone, and only one peculiar 

 genus, namely, the grass Pleuropogon.^ Of the 7G2 found 

 south of the circle, all but 150 have advanced beyond lat. 40" 

 N. in some part of the world ; about 50 of them are identified 

 as natives of the mountainous regions of the tropics, and 105 

 as inhabiting the south temperate zone. 



" The proportion of species which have migrated southward 

 in the Old and New World also bear a fair relation to the 

 facilities for migration presented by the different continents." 

 The tables given to illustrate this " present in a very striking 

 point of view the fact of the Scandinavian flora being the 

 most widely distributed over the world. The Mediterranean, 

 south African, Malayan, Australian, and all the floras of the 

 New World, have narrow ranges compared with the Scandi- 

 navian, and none of them form a prominent feature in any 

 other continent than their own. But the Scandinavian not 

 only girdles the globe in the arctic circle, and dominates over 

 all others in the north temperate zone of the Old World, 

 but intrudes conspicuously into every other temperate flora, 

 whether in the northern or southern hemisphere, or on the 

 Alps of tropical countries. ... In one respect this migration 

 is most direct in the American meridian, where more arctic 

 species reach the highest southern latitudes. This I have 

 accounted for (' Flora Antarctica,' p. 230) by the continuous 

 chain of the Andes having favored their southern dispersion." 



In presenting the actual number of arctic species, and in 

 delineating their geographical ranges, the question, what are 

 to be regarded as species, becomes all-important. As to this, 

 it does not so much matter what scale is adopted, as to know 

 clearly what the adopted scale is. Here we are not left in 



1 Douglasia is mentioned in another place (p. 2G9) ns an absolutely pe- 

 culiar arctic or arctic-alpine genus of eastern America. But we have con- 

 sidered this genus as identical with Gregoria, of Duhy. It would appear 

 as if these two genera were established in the same year, since Lindley 

 himself, in the "Botanical Register," refers to Brando's Journal for Jan- 

 uary, 1828, for his original article. But this article will be found in the 

 volume of that Journal for 18'J7 ; so that the name Douglasia is to be 

 adopted, if the genus is sufficiently distinct from Androsace. 



