AS AIDS IN THE DETERMINATION OF SPECIES. 61) 



Thus there is a remarliable resemblance, for instance, between the sections of 

 the petioles of E. calophylla and E. ficifolia, and the question arises — Are they to be 

 regarded as distinct species or not ? 



The principal differences between E. ficifolia and E. calophylla, as given by 

 Baron von Mueller in his " Eucalyptographia" (Dec. 7), are as follows: — 



E. ficifolia. 

 Tree. — Of less height. 

 Bark. — Somewhat more deeply furrowed. 

 Leaves. — Proportionately not quite so broad, but longer. 

 Flowers. — Mostly larger. 

 Calyces. — Assume a reddish hue. 

 Fruits. — Less turgid. 



Seeds. — Much paler in colour, have a smaller kernel, and are provided with con- 

 spicuous appendicular membranes. 



If the leading specific differences of the same authority be compared, it will be 

 found that the crimson filament and the pale seeds, with a long membrane, of E. fici- 

 folia are the principal offsets against the pale-yellowish, rarely pink filaments, and 

 dark membraneless seeds of E. calophylla. 



Here the differences are comparatively small, but the characters, such as they 

 are, being permanent, are considered sufficient to fix this as a distinct species. 



If we turn to the characters revealed by the petiole, the same remark applies. 



The broad differences separating /c//b//rt from calophylla are: — • 



Slightly thicker epidermis, with a strong development ofhypoderm, although 

 there are indications of something similar to the latter in calophylla. 



Cortical Cavities. — Much fewer and smaller. 



Central Canals. — Smaller. 



Vessels. — About the same size, slightly larger, but weaker development of 

 wood. 



Such permanent differences probably entitle E. ficifolia to specific rank, but it 

 will be observed that the differences are just such as might arise from the same kind 

 of tree, from any cause, becoming dwarfed and stunted in growth. 



Both belong to the furrowed bark series (Schizophloiaj), have anthers opening by 

 parallel slits (Parallelanthera;), and pollen-grains of the same size. The fruits in both 

 are urn-shaped, and their habitat is confined to Western Australia. 



