ANNOTATIONS AND ADDITIONS. 141 



current which turns towards the southern pole, and on 

 the temperature of the Southern Hemisphere. Some of 

 the noblest forms of tropical vegetation, for example the 

 tree-ferns, advance south of the equator as far as the parallels 

 of 46, and of even 53; whereas north of the equator they 

 are not found beyond the tropic of Cancer. (Eobert Brown, 

 Appendix to Flinders' Yoyage, p. 575 and 584; Hum- 1 

 boldt, de distributione geographica Plantarum, p. 81-85.) 

 Tree-ferns thrive extremely well at Hobart Town in Van 

 Diemen Island, (lat 42 53'), where the mean annual tem- 

 perature is 9 Eeaumur, or 5 2. 2 Fahrenheit, and is there- 

 fore l.6 Eeaumur, or 3.6 Fahrenheit, less than that of 

 Toulon. Rome is almost a degree of latitude farther from 

 the equator than Hobart Town, and has an annual tem- 

 perature of 12.3 E., or 59.8 Fahr.; a winter tempera- 

 ture of 6.5 E., or 46.4 Fahr., and a summer temperature 

 of 24 E., or 86 Fahr. ; these three values being in Hobart 

 Town 8.9, 4.5, and 13.8 E., or 52.0, 42.2, and 63. 

 Fahr. In Dusky Bay, New Zealand, tree-ferns grow in 

 S. lat. 46 8', and in the Auckland and Campbell Islands, 

 even in 53 S. lat. (Jos. Hooker, Flora Antarctica, 1844, 

 p. 107.) 



In the Archipelago of Tierra del Fuego, where, in the 

 same latitude as Dublin, the mean winter temperature is 

 0.4 Eeaumur, (33 Fah.) and the mean summer tempera- 

 ture only 8 E., or 50 Fahr., Captain King found the 

 "vegetation thriving most luxuriantly in large woody -stemmed 

 trees of Fuchsia and Veronica" ; while this vigour of vege- 

 tation, which, especially on the western coast of America 



