DERIVATION OF THE FLORA AND FAUNA 263 



The systematical position of Callitrichc lias been discussed man)- times, but 

 we know notliin<j; of its history or where it started. The ^enus is world-wide, but 

 many species are not wide-sjiread and some are quite local, among them C. Lecli- 

 leri, which ma\- have been carried to Juan Fernandez from the mainland by 

 accident. 



The tribe Collctieae of the otherwise wide-ranging Khamnaccae is called 

 austral-antarctic by SCSSENGUT (Natiirl. Pflanzenfam. 2nd ed.); except Adolphia 

 (Mexico-U.S.A.) the genera are distributed over Andean and extratropical S. Amer- 

 ica, centering in Chile, and Collctia spartioides finds its place with the Andean 

 element. It should be mentioned that Discaria (ii) extends south to Fuegia and 

 reappears in Australia (i) and New Zealand (i), suggesting transantarctic migra- 

 tion from America. 



The family lUacourtiaceac is tropical; Azara is neotropical with about 19 

 species in Chile, i in Brazil and i in Argentina. The tribe to which it belongs 

 is well developed in the south hemispliere: tropical America and Africa, Mada- 

 gascar and neighbouring islands, Asia, New Guinea and [Xylosma] Oceania to 

 Hawaii, but Antarctica may not at all be involved in its history. 



Myriaccae. A \ery large world-wide and tropical-subtropical family. Of the 

 subfamily Myrtoideae, some 2400 species, 75 % are American, the remainder scat- 

 tered over Asia, Africa, Australia and Oceania. The Leptospermoideae, some 850, 

 are restricted to Australasia with the single exception of Tepnalia, monotypical 

 and endemic in the Chilean rain forests, south to West Patagonia, a most inter- 

 esting case of disjunction. Berry [26) regards the family to be of American ori- 

 gin and to have attained its present distribution before the close of the Creta- 

 ceous. Basing his conclusions on fossil evidence he thinks that during the cooling 

 down of the climate during late Tertiary, the ancestral stock of Myrtoideae with- 

 drew from North America to the neotropical zone; the Australian Leptospermo- 

 ideae represent the remnants of the Cretaceous radiation during which numerous 

 new types became evolved. Some of these eventually invaded Antarctica and 

 Tepualia survives on Chilean soil. 



The Juan Fernandez Myrtoideae are closely linked to Andean t\'pes. For Ugni 

 Selkirkii and Myrteola >iunu)nilaria see p. 206. XothoDiyrcia, now restricted to Masa- 

 tierra, may or may not have inhabited a larger area. Myrceiigenia has about 20 

 species in Chile. 



Gunne7'aceae (often placed as a subfamily under Halorrhagidaceae) is a classi- 

 cal example of a tricentric Antarcto-tertiary type. Its long and complicated history 

 is reflected in its taxonomic differentiation; C"//;/;/^;-^? is composed of 6 subgenera. 

 Paugue is the largest with 10 species ranging from Costa Rica to S. Chile, i in 

 Brazil, 3 in Juan F'ernandez and 2 in Hawaii. Perpensuiii is monotypical with 

 separate varieties in S. Africa, British E. Africa and Madagascar, Ostenia an aber- 

 rant monotype endemic in Uruguay. Misaiidra includes 3 species, one extending 

 from Colombia to Fuegia and Falkland, one restricted to the S. Chilean Andes 

 and one to subantarctic America; Milliga}iia has 8 species in New Zealand and 

 I in Tasmania. The monotypical Pseudogumicra inhabits New Guinea, Java, Su- 

 matra and the Philippines. No subgenus is found in more than one sector. It is 



