14 



MR. J. G. BAKER ON THE GEOGRAPHICAL DISTRIBUTION OF FERNS. 



characteristically temperate, but plants which have their head quarters within the tropics 



and occur les - abundantly outside 1 1 iem. Of well-marked truly temperate species common 

 to tli ipe and Australia we may note Todea barbara, Asplenium bulbtferum, and fiac- 

 ekinm, and, amongst those common to the Cape and temperate South America, Polypo- 

 (!i/rm in unit m and Lomaria Magellanica. To meet with Aspidium falcatum and Asple- 

 nium variant again we must go from the Cape to the Himalayas, and for Asplenium 



benewn and I'clheaandromedafolia to North Am 



Of well-marked species confined 



to Africa, which have their head quarters here but pass slightly within the tropic, Pteris 

 Jlabi'llahi, Mohria caffrorum, Cyathea Dregei, and Notochlcena incequalis are examples. 

 Considering the smallness of the tropical- African list, the addition to that of this district 

 of 89 tropical species is large ; hut several of them inhabit Mauritius and Madagascar, and 

 «lo not pass further south than Natal. 



We have included Tristan dAcunha in this district. This little island is not more 

 tlian twenty miles in circumference, and is situated in the midst of the Atlantic, nearly 

 in the latitude of Cape Town and Monte Video, where the distance between the two con- 



om --fifth of the whole circumference of the globe 



It is about ten deg 



to Africa than America, and is remarkable for having the flora in which, as com 



p;ired with all others that are known, the ferns are most nearly upon 



quality 



number of species with the flowering plants. The following is its fern-list, 23 species 

 Lyoopodiacese not included, the number of flowering plants enumerated by Captair 



Carmichael (Linn. Trans, vol. xii. p. 483) being 29 : 



*IIymenophylIum seruginosum. 

 Adiantum aethiopicum. 

 Pteris incisa. 



Blechnum australe, 

 Lomaria alpina. 

 Boryana. 



Asplenium obtusatum. 



Aspidium coriaceum. 

 *Polypodium aquilinum 



punctatum 

 australe. 



* 



erectum. 

 monanthemum. 



medi 



mm. 



Trichomanes tenerum. 

 N ephrodium tomentosum 



Gymnogramme cheilantboides 



♦Vittaria stricta. 

 Acrostichum conforme. 



hybridum. 

 spathulatum. 

 succissefolium 



Opliioglossum bulbosum 



It is curious to analyze this list and compare it with that of St. Helena. Here we have four 

 peculiar species (those marked with an asterisk), three only found elsewhere in the Mauri- 

 tius, nine which are both Cape and American, six which are American but not Cape, and 



hich is nominally Cape but not American, but very doubtfuUy distinct from a com 



mon American plant 



There are only 18 species altogether which are common to tern 



perate South America and the Cape ; and here we have half of them on this little isolated 



"ay island. Whilst St. Helena, which is much nearer a continent, has more than 

 >>lt ite terns peculiar, here we have only a sixth of them ; and although it is nearer Africa 

 than America, the affinity is considerably closer with the latter. It is included by Dr. 

 Hooker m the so-called Antarctic flora. 



