186 BERRY— LOWER EOCENE FLORA OF [April 25, 



affinities decrease from Asia toward Africa and also through Poly- 

 nesia. A number of genera (Toona, Xylocarpus, Cipadessa, Melia) 

 extend from Africa through Asia to Malaysia. Two genera are 

 peculiar to Australia (Synoum^ Oivenia) and two to Polynesia {Va- 

 vea, Meliadelpga). There are thirteen monotypic genera of which 

 six are African and seven Asiatic. From the distribution of the 

 existing species De Candolle^- infers that southern Asia is the center 

 of radiation of the family. I am inclined to think however that the 

 reverse is probably true since the oldest known forms, except the 

 entirely doubtful Cedrelospermites of Saporta from the Valanginian 

 of Portugal, are American, and the widespread existing American 

 representation of the family seems to comprise the specifically mul- 

 tiplied descendents of the original stock already represented in the 

 Wilcox flora. 



The Asiatic genera would represent immigrants into that area or 

 forms evolved there. The Polynesian and Australian forms are 

 much localized derivatives of the Indian stock and unless the peculiar 

 species of New Caledonia could not reach that region except by a 

 land connection it may be inferred that this Asiatic radiation was 

 relatively recent. 



The fossil species are unfortunately few in number. So far as 

 I know the only fossil species of Carapa is that found in the Wilcox. 

 Its occurrence in the early Eocene is at least a factor in explaining its 

 present distribution in both the American and West African tropics. 

 The fact that Carapa procera is common to these two areas may sug- 

 gest that all of the African species are recent immigrants, but it is 

 more probable that there are unrecognized specific differences in this 

 form in the two areas and that the present disconnected distribution 

 is an example of survivors from the early Tertiary radiation. An- 

 other genus with a modern distribution like Carapa is the genus 

 Moschoxylon Jussieu (made a section of TricJiilia Linne by Harms 

 in Engler and Prantl) which has about 60 species of tropical Amer- 

 ica and West Africa. This has furnished two fossil species de- 

 scribed by Engelhardt from the early Tertiary (Eocene or Oligo- 

 cene) of Chili. The genus Ccdrcla, sometimes made the type of an 



32 De Candolle, C. de, " On the Geographical Distribution of the Melia- 

 cese," Trans. Linn. Soc. Lond., 2 ser., Bot., Vol. i, 1880, pp. 233-236, PI. 30, 31. 



