BY E. C. ANDREWS. 545 



Australia appears to have been connected with Asia during the 

 Jurassic and the Lower Cretaceous, but during some part of the 

 Upper Cretaceous, it seems to have been cut off from Asia, and it 

 is doubtful whether there has been any direct communication be- 

 tween the two continents since that date. 



Morphological Characters common to the Myrtace*:. 



Upon an examination of the family, it will be at once apparent 

 that certain morphological characters run throughout the various 

 genera. In proportion to the xerophytic nature, or harsh environ- 

 ment, of the genus or species, so are the characters common to the 

 family obscured in that genus or species, and the morphological 

 clue is not readily seen, but, on the other hand, in proportion as the 

 fertile tropics are approached, especially those of America, so, in 

 the Myrtacese of these regions, is the morphological clue most 

 easily retained. In those genera which are partly depauperate in 

 type, such as Baeckea, it may be noted that the species which are 

 not depauperate, have more points in common with the family, as 

 a whole, than those species of the genus, which live amid harsher 

 conditions. Eucalyptus possesses a cap to its young flower, and, 

 with this protection to its reproductive organs in their earlier 

 stages, it has accommodated itself to various climates and soils, and 

 it departs markedly from the generality of the family in many 

 particulars. The extremes are probably exhibited by Chamaelau- 

 ciese and Myrteae respectively, the one being confined practically to 

 the fertile tropics, the other, in great measure, to the relatively 

 sterile tracts of Western Australia. The capsular genera occupy 

 a middle position, and exhibit, on the one hand, a great resemblance 

 to Myrteae, and, on the other hand, to the Chamaelaucieae. 



The question then arises, what were the characters of the earlier 

 types'? Are we to conclude that some form, such as Eucalyptus, 

 was the early type, that it had a cosmopolitan range, and that, 

 later, it became extinct in the world generally, nevertheless flourish- 

 ing in Australia, and giving rise, in the meantime, to the fleshy- 

 fruited genera, all of which show a marvellous likeness to each 

 other, but very little resemblance to the Eucalyptus ? Or are we to 

 consider that the more or less xerophytic types, such as Eucalyp- 



