EUCALYPTUS TREES. 23 
an inch. Outer part of the seed (testa) thick, somewhat spongy 
or corky ; kernel consisting of an imperfectly divided turgid 
cotyledonar mass and a short radicle. 
On forest-rivers of Hast Gippsland, thence dispersed through 
the moist wooded country of all Eastern Australia. 
The tyro having now obtained an insight into the main- 
characteristics of the Myrtaceze and having learned to recognise 
some of their leading forms, requires yet to trace them to the great 
main-division and particular subdivision of the system of plants, 
in which they hold a place. It is in the first of the three main- 
divisions, the Dicotyledonee, into which the order Myrtaceze must 
also be inserted. Dicotyledonous plants are characterised by the 
following principal notes :—The stem when perennial consists of 
separable bark, distinct wood and central pith ; additional annual 
concentric layers are formed between bark and wood, the growth 
being therefore outward ; hence also the Greek name Exogene 
for dicotyledonous plants. Leaves or their stalks generally arti- 
culated at the point of insertion. Veins of leaves usually branched. 
Corolla very frequently present, as well as the calyx consisting 
prevailingly of five or four divisions. Genuine stamens, pistils 
and embryonate seeds always developed. Cotyledons almost 
constantly two and opposite or very seldom three or more in a 
whorl or obliterated. First rudimentary leaves from the germi- 
nating seed always opposite. This is the largest of the three 
main-divisions, into which plants are classified. 
If we now contrast the characteristics of the second main- 
division, that of the Monocotyledonee, with the characters of the 
dicotyledonous plants, we will find: the stem when perennial 
without circular arrangement of bark, wood and pith, the woody 
fibres and vascular tubes being dispersed through the cellular 
tissue ; the increase of growth not distinctly in an exterior zone ; 
hence in contradistinction the synonym Lxdogene for monocoty- 
ledonous plants. Leaves or their mostly clasping stalk generally 
not articulated at the point of insertion. Veins of the leaves 
usually closely parallel. Division of the calyx prevailingly into 
six parts, the three inner not rarely petal-like, but no real corolla 
developed ; in grasses and allied plants also the calyx absent, 
