8 EUCALYPTUS TREES. 
expedition ; and it derives its name from two Greek words, alluding 
to the lid (Fig. IL. 1), which covers the flowers before expansion. 
Several other species of Eucalyptus were described by Sir James 
Smith, before the E. globulus became known. The genus Huca- 
lyptus comprises about 150 species, all Australian except a few 
from the Indian Islands and New Guinea, none extending to New 
Zealand and New Caledonia. Next to Acacia it is in Australia 
the genus richest in species. For grouping these numerous spe- 
Fie. I. cies together 
into systematic 
divisions, so as 
to facilitate the 
recognition of 
any of them, 
two methods 
are available. 
For one of these 
methods the 
nature of the 
bark can be 
adopted as af- 
fording a pri- 
mary and often 
widely conspic- 
uous character- 
istic ; for the 
second method 
of arrangement 
the nature of 
. the anthers 
(Fig. IL. 3, top) 
can be chosen 
for systematic 
main-distinctions. In the first case we have to place the Blue 
Gum-tree into the series with smooth barks, the outer cortical 
layers successively seceding and leaving the surface of the bark 
smooth; in the second case we have to refer this species to a 
