I9I4-] SOUTHEASTERN NORTH AMERICA. 223 



moide?e, comprises the Leptospermae with 28 genera and about 700 

 species and the Chamseleuciere with 12 genera and about 165 species. 

 Both of these tribes are even more strikingly Australian than the 

 Myrtoideae are American. The Chamnaeleucieae are entirely Aus- 

 tralian and mainly confined to western Australia. The Leptospermae 

 have a single monotypic genus in Chili and the distribution of the 

 other members of this tribe suggest the probability that it should 

 be placed in some other alliance, since with the exception of Metro- 

 sideros, which is represented in Africa, and the genus Baeckca which 

 reaches the Asiatic mainland, all of the genera are confined to Aus- 

 tralia or the surrounding islands southeast of Asia. 



In a recent paper Andrews 44 has presented some interesting sta- 

 tistics of distribution and an ingenious theory of the history of the 

 family. He considers that the original stock was arborescent or 

 shrubby with entire, simple, opposite, penniveined leaves with dots 

 and intra-marginal aerodrome veins ; with the calyx lobes and petals 

 imbricate, probably in fives : flowers regular, solitary or in cymes ; 

 stamens indefinite, numerous, free, with versatile, 2-celled anthers ; 

 ovary inferior with two or more cells ; style simple ; fruit inferior, 

 crowned with persistent limb of calyx, indehiscent, succulent or fleshy 

 (rarely dry); albumen none; cotyledons thick and fleshy, with a 

 short radicle. 



From the character of Cretaceous climates this or some other 

 theoretical prototype flourished in a mesophytic environment 

 Among modern groups the nearest approach to this theoretical stock 

 is furnished by the Myrtoideae which are fleshy fruited, most numer- 

 ous in species, and widely spread in the equatorial regions, with over 

 75 per cent., however, confined to America. The existing Myrtaceae 

 with capsular fruits representing the extreme of specialization in the 

 family are Australian while the Chamaelaucieae standing in an inter- 

 mediate position between the two preceding groups are almost wholly 

 confined to western Australia. 



These are the facts of modern distribution. Their interpretation 

 may be various. Andrews (op. cit.) from a study of the present dis- 

 tribution, geologic climates and the geological history of the Austra- 



44 Andrews, E. C, " The Development of the Natural Order Myrtaceae," 

 Proc. Linn. Soc. N. S. Wales, Vol. 38, Pt. 3, 1913, pp. 529-568. 



