326 PHYSIOGNOMY OF PLANTS. 



of vegetation;" and on the other hand, " instances of a sudden 

 change in the vegetation unaccompanied by any diversity of geolo- 

 gical or other features." (Joseph Hooker, Botany of the Antarctic 

 Voyage of the Erebus and Terror, 1844, p. 210.) Is there any 

 species of Erica in Central Asia ? The plant spoken of by Saunders 

 in Turner's Travels to Thibet (Phil. Trans, vol. Ixxix. p. 86), as 

 having been found in the Highlands of Nepaul (together with other 

 European plants, Yaccinium myrtillus and V. oxycoccus), and de- 

 scribed by him as Erica vulgaris, is believed by Robert Brown to 

 have been an Andromeda, probably Andromeda fastigiata of Wal- 

 lich. No less striking is the absence of Calluna vulgaris, and of all 

 the species of Erica throughout all parts of the Continent of Ame- 

 rica, while the Calluna is found in the Azores and in Iceland. It 

 has not hitherto been seen in Greenland, but was discovered a few 

 years ago in Newfoundland. The natural family of the Ericaceae 

 is also almost entirely wanting in Australia, where it is replaced by 

 Epacridese. Linnaeus described only 102 species of the genus Erica; 

 according to Klotzsch's examination, this genus really contains, after 

 a careful exclusion of all mere varieties, 440 true species. 



() p. 241." The Cactus fo 

 If we take the natural family of the Opuntiaceae separated from 

 the Grrossulariaceae (the species of Ribes), and, viewed as it is by 

 Kunth (Handbuch der Botanik, s. 609), we may well regard it as 

 belonging exclusively to America. I am aware that Roxburgh, in 

 the Flora Indica (inedita), cites two species of Cactus as belonging 

 to South Eastern Asia; Cactus indicus and C. chinensis. Both 

 are widely disseminated, and are found in a wild state (whether they 

 were originally wild or have become so), and are distinct from Cactus 

 opuntia and C. coccinellifer; but it is remarkable that the Indian 

 plant (Cactus indicus) has no ancient Sanscrit name. Cactus chinensis 

 has been introduced in St. Helena as a cultivated plant. Now that 

 a more general interest has at length been awakened on the subject 

 of the original distribution of plants, future investigation will dispel 

 the doubts which have been felt in several quarters respecting the 

 existence of true Asiatic Opuntiaceae. . In the animal kingdom par- 

 ticular forms are found to occur singly. Tapirs were long regarded 



