I9I4.] SOUTHEASTERN NORTH AMERICA. 169 



tralian species are to be regarded as migrants from the preceding 

 area. There are upwards of loo species and 6 peculiar genera in 

 tropical Africa ; and America has about 200 species and 10 peculiar 

 genera. These are all confined to the tropics except for a species of 

 Anona which reaches the coast of peninsular Florida and for the 

 genus Asimina with six or seven species of shrubs and small trees of 

 the south Atlantic and Gulf States. One of these, Asimina triloba 

 Dunal, is hardy as far north as New York and has the distinction of 

 growing the farthest distance from the equator of any existing mem- 

 ber of the family. The fossil record of the Anonacese is very incom- 

 plete, only the genera, Anona Linne and Asimina Adanson being 

 known with certainty. Both of these genera are present in the Wil- 

 cox flora. 



The genus Anona has from fifteen to twenty fossil species five of 

 which are also represented by seeds. The oldest is a species described 

 from the Dakota sandstone. There is a second species in the late 

 Cretaceous or Early Eocene of the Rocky ^Mountain province. The 

 flora of the Wilcox affords a glimpse into the true stage of evolution 

 of Tertiary floras in that expanded belt of the American equatorial 

 region which was the center of radiation of so many recent types. 

 There were three exceedingly well marked species of Anona along 

 the Wilcox coast and their leaves are very common at some localities 

 although no seeds have as yet been discovered. I assume that these 

 Wilcox forms had habits similar to those of the majority of the ex- 

 isting species, exemplified by our Florida Anona glabra Linne, or 

 Pond Apple, which frequents shallow fresh water swamps, low shady 

 hammocks, or stream borders near the coast. Other species occur 

 in the low coppice association or on edges of brackish swamps on the 

 Bahamas. The cultivated species, as for example the American 

 Anona reticulata Linne which is planted in Guam often spreads nat- 

 urally along the inner beaches, while attempts to introduce others of 

 the most highly esteemed American species in the Orient have failed. 

 From its prevalence among the existing species the habit of growing 

 in wet shaded soils is evidently an old one, and since the Wilcox 

 Anonas are associated with a strand flora, the assumption that they 

 grew on the inner beaches or the shaded and more swampy edges of 

 lagoons, possesses every degree of probability. 



