386 REVIEWS. 



and it is a questionable morphology which would promote the 

 capitulum of a Thistle or a Dandelion to the head of the class. 



We remember an interesting^ lecture, in which, recoofnizino- 

 the dominant part which the northern hemisphere and its 

 boreal lands, with their favorable configuration, have un- 

 doubtedly played in floral distribution, it was inferred that 

 the role of the southern had always been comparatively in- 

 significant. But a great deal may have happened in the 

 austral regions before this boreal supremacy was established. 

 Mr. Ball several years ago brought forward his doctrine of 

 the very high antiquity of our actual temperate and alpine 

 floras, of their coexistence in highly elevated regions of low 

 latitudes even in early times. So now, applying his former 

 conclusions to the southern hemisphere, and to " a period 

 remote even in geological language," he notes that " the spe- 

 cial generic types of the antarctic flora " " belong without 

 exception to the great groups or natural orders which are 

 now almost universally diffused throughout the world ; and 

 the ancestral types from which they originated were probably 

 carried to that region at a remote period, when the physical 

 conditions of the earth's surface were widely different from 

 those now prevailing." " Various considerations tend to the 

 conclusion that the dispersal of the chief cosmopolitan genera 

 of plants may have coincided with the period of the older 

 secondary rocks ; and at that period physical agencies far 

 transcending those of our experience prevailed throughout 

 the earth. If the ancestors of the antarctic types of vegeta- 

 tion were then established in a south polar continental area, 

 and were developed from them by gradual modification, I 

 see no difficulty in believing that they may have maintained 

 themselves through successive gradual changes of physical 

 conditions within the same region, and even that some may 

 still survive within the Antarctic Circle." 



Whether or not one accepts the idea of such high geo- 

 logical antiquity which Mr. Ball claims for what he calls Cos- 

 mopolitan types, we must wholly agree with him in his use of 

 this name for them, in preference to that of the Scandinavian. 

 The latter term was used by Hooker before the relation of 



