of the Galapagos Archipelago. 241 



on approaching the frigid zone, from Madeira (lat. 32°) 3-j, Azores (iat. 38°) 

 ^, Great Britain (lat. 50°-57) 1, Shetland (lat. 60°) ^, which is the maximum 

 for the northern hemisphere. In the arctic regions, on the other hand, all 

 the proportions obtained, either from isolated localities (except Melville Island) 

 or from extended tracts, tend to confirm Mr. Brown's first theory, that the pro- 

 portion is again inverted. Thus that of Iceland (lat. 65°) is ^, Spitzbergen 

 (lat. 78°*80) ^, east coast of Greenland ^, the Arctic American islets (lat. 68°) 

 ^, Baffin's Bay (lat. 70°76) if. Port Bowen and Prince Regent's Inlet (lat. 74°) 

 ^. To this regular progressive decrease, Melville Island offers the only ex- 

 ception, its proportion being that of the Shetlands*. 



From the above facts it may be assumed that equable, temperate, and rather 

 humid climates are most favourable to a Monocotyledonous vegetation, for it 

 diminishes both under the extreme cold of the arctic zone and the great heat 

 of the tropics ; on the other hand increasing towards the southern temperate 

 and antarctic zones, where such conditions are best fulfilled, proportionally 

 with the latitude, to as far south as a Phsenogaraic vegetation extends. 



With regard to the amount of peculiarity existing in the two great divisions 

 of flowering plants in any country, it is a curious subject, but one towards the 

 illustration of which little has been done. Generally speaking the Monocoty- 

 ledones present much the lesser proportion of novelty ; but this is not the case 

 in the Galapagos, nearly one-half of whose Monocotyledonous plants (10 out 

 of 22) are confined to that group : whence it may be inferred, that the paucity 

 of this division there in reference to the whole Flora is owing in some measure 

 to obstacles to the transport of seeds from the continent. 



The prevailing natural orders in the Galapagos are the Ferns, containing 

 28 species ; Compositce 28 ; Leguminosce 24 ; Euphorbiacece 18 ; Rubiacece 15 ; 

 Solanece 13 ; Graminece 12 ; Amaranthacece 10 ; Verbenaceoe 9 i Cyperacece and" 

 Boraginece each 7 "• of the other 43 orders none are so extensive, or are other- 

 wise worthy of particular mention, except Cordiacece, of which there are six 

 species, only one or perhaps two of which inhabit the adjacent continent. All 



* With regard to Melville Island, it should be borne in mind that it is beyond those limits up to which 

 every degree of latitude is marked by some one or more peculiar species of plant which is not found be- 

 yond it. It is on the verge of the extinction of terrestrial vegetation in that longitude, and therefore pre- 

 sents us with such species only as can struggle successfully against the climate they there encounter, j 



