BY E. C. ANDREWS. 547 



the deduced original Myrtacean type ; and the typical geographical 

 conditions of the Cretaceous Period. 



The areas of greatest density, to-day, are Tropical America, and 

 warm, temperate Australia. 



The families most closely related in morphological characters to 

 the Myrtaceae, are the Combretaceae, the Melastomaceae, the Rhizo- 

 phoreae, and the tribe known as Lecythideae, included by Bentham 

 and Hooker under Myrtaceae. Combretaceae is a tropical family, 

 Rhizophoreae is also mainly a tropical family, while Melastomaceae 

 forms a large family, and is found mostly in the tropics, chiefly 

 American. 



Upon a careful comparison of various members of the Lecythi- 

 deae, and a knowledge of their distribution, the Writer has con- 

 sidered it advisable to treat it as a family distinct from Myrtaceae. 

 For, if one considers its confinement to the fertile tropics, and its 

 development in freedom from those harsh conditions which have 

 left their traces so indelibly upon the majority of Australian Myr- 

 taceae, one would expect it to exhibit morphological characters 

 more in harmony with those of the Myrtaceae of the fertile tropics, 

 and to retain the morphological clue, which is so easily traced in 

 Eugenia, Myrtus, and allied genera in Myrteae. Nevertheless, the 

 clue is not at all easily retained in Lecythideae. The characteristic 

 opposite and dotted leaves are missing, the general appearance of 

 the leaves otherwise is not like those of Myrteae, the flower-spikes 

 are unfamiliar in connection with Myrtaceae, and the fruit-forms 

 are not at all suggestive of Myrtaceae. Nevertheless, Lecythideae 

 must be considered as a closely allied family. 



The consideration of the home of the family, from this double 

 point of view alone, strongly suggests that the Myrtaceae originated 

 in the tropics, but the questions then arise: — 



(a) Did the Myrtaceae originate in the Old World tropics, then 

 extend to America and Australia, and become strongly differenti- 

 ated in these localities, while evolution lagged in the intermedi- 

 ate area, owing to severe competition? or: — 



(b)Did Myrtaceae originate in Tropical America, and spread 

 thence to Asia and Australia? 



