134 



MIOCENE CLIMATE. 



If we next consider the tropical forms, we remark first some 

 ferns (see vol.i. p. 322), the feather-palms, the Parana (fig. 176, 

 vol. i. p. 354), fig-trees, Brazil-wood trees (Casalpinice) , Cassias, 

 and true Acacias. These trees could not have supported the 

 winters of the temperate zone ; but it is very likely that a climate 

 such as that of Madeira may have sufficed for them; for at 

 present the caoutchouc-tree (Ficus elastica), the Eugenics, the 

 Casalpinice , Cassias, and true Acacia (such as A. lophanta and 

 dealbata) flourish admirably in the gardens of Funchal, where 

 the pisang, the Indian mango, the guava, and pine-apples also 

 ripen their splendid fruit. Of the palms those with fan-shaped 

 leaves extend into the warm zone ; and the dwarf palm (Chama- 

 rops humilis) grows on the southern coasts of Spain, Sicily, and 

 Naples, and has its northern limit near Nice (in latitude 

 43 41' N., with a mean temperature of 60'2 Fahr. or ] 5-6 C.) . 

 The Chinese dwarf palm (Chamcerops excelsa, Thunb.) is still 

 hardier, and supports the winter of the south of England. In 

 America these dwarf palms are represented by the swamp-palm 

 (Sabal Adansoni, Guerns.), which occurs very plentifully in the 

 swamps of Florida, Georgia, and Carolina, and extends to 

 35 N. lat. This palm bears the winter at Montpellier. The 

 umbrella-palm of the West Indies (Sabal umbraculifera, Jacq., 

 sp.) is of larger size ; but its distribution is restricted within nar- 

 rower limits. The feather-palms of the Miocene differ greatly 

 from all existing forms. Two of them constitute peculiar ex- 

 tinct types ; two others may be arranged in existing tropical 

 genera. But we are acquainted with no existing species homo- 

 logous with or nearly related to them, and they may have been 

 organized for a cooler climate than their living but remote con- 

 geners. Among the existing feather-palms, the American wax- 

 palm seems to require the least warmth, since it ascends upon 

 the Cordilleras to considerable elevations, where the summers 

 are cool and the winters are not cold, the extremes of tempera- 

 ture being much softened down between the tropics. In the 

 Old World the date-palm, of all feather-palms, extends furthest 

 towards the north ; but even in the hottest districts of Europe 

 (with the sole exception of Elche in Spain) it rarely ripens its 

 fruit. It requires an annual mean temperature of at least 68 F. 

 (20 C.) to bring its fruit to perfect maturity. 



