E. V. Wulff —96 — Historical Plant Geography 



Transvaal and other adjacent parts of South Africa. Out of seventeen 

 species and thirteen varieties of Menodora, Steyeemark (1932), a 

 monographer of this genus, found that "nine species and eleven vari- 

 eties occur in North America, six species and one variety in South 

 America, and two species and one variety are found in Africa, one of 

 the species, M. heterophylla, being found in North America and having 

 its variety in Africa. There are, accordingly, three distinct areas of 

 distribution: (/) southwestern United States and Mexico, (2) central 

 and southern South America, and (3) South Africa" (p. 100). All 

 these regions are characterized by arid or semi-arid conditions. Steyer- 

 MARK considers that the area of the genus Menodora, and consequently 

 of the bees connected therewith, "in all probability had a more con- 

 tinuous geographical range at least before the end of the Cretaceous 

 period", and that "the most logical source of evidence explaining this 

 present interrupted distribution lies in the postulation of a land-bridge 

 once connecting South America and Africa" (p. 104). 



A number of identical discontinuous areas of animals and plants 

 are cited by Reinig (1937), who summarizes the data of Dr. L. S. 

 Berg and others in his book, "Die Holarktis". Among such areas are 

 those having the following distribution: Europe -eastern Asia, Eurasia- 

 America, and Europe-North America. Reinig believes that these 

 areas had their origin as a result of conditions during the Ice Age. 



Evidence for the existence of a land-bridge between Africa and 

 India is provided not only by floristic but also by faunistic data. Thus, 

 Scott (1933), on the basis of a comparison of the insect fauna and 

 flora of the Seychelles and adjacent islands, comes to the conclusion 

 that these islands "are not typical oceanic islands, but of an ancient 

 continental type. ... The high percentage of endemic forms in both 

 flora and fauna indicates a biological association which has endured 

 since the remote past, but which has existed throughout the archi- 

 pelago as a whole; there has been little formation of distinct species in 

 the individual islands, the separation of which has probably been com- 

 paratively recent. . . . However many be the endemic plants and 

 animals which have died out, those which persist are the reinains of the 

 flora and fauna of a much larger, almost vanished, land" (p. 381). 

 The presence of a considerable percentage of species of plants and 

 animals having related forms in Africa, on the one hand, and India, 

 on the other, indicates that this archipelago constitutes the remnants 

 of a land-bridge formerly connecting Africa and India. The fact that 

 "the element with African afiinities in the endemic fauna is of more 

 recent origin than the element with Indo-Australian affinities" (p. 382) 

 points to the longer persistence of a connection with Africa, that with 

 India having been broken at a considerably earlier period. 



The foregoing examples suffice to show what great significance for 

 historical plant geography may be the checking of floristic data with 

 those of zoogeography. 



Rust Fungi as an Index of the Distribution of their Plant Hosts: — 

 In the works of Mordvilko (1925, 1926) we have valuable data ob- 

 tained by a comparison of the distribution of rust fungi and of their 

 hosts. In this case the possibility of botanico-geographical conclusions 



