34 
CENTKAL HALL. 
seed. Here we find the smaller class of Angiosperms, known 
as Monocotyledons, and characterised by a single seed-leaf or 
cotyledon, and foliage leaves with more or less parallel veins, 
without the irregular network found in a dicotyledonous leaf. An 
upper series in the wall-case illustrates the leaf, while below 
the characters of the stem and root are shown. Some anatomi- 
cal drawings are placed in the upper part of the case. The 
right-hand half of the central case contains specimens of 
the flower, fruit, and seed ; wax models are here frequently 
employed. Among these will be noticed many grasses and 
sedges, which, with the palms, aroids, orchids, and liliaceous 
plants, form the bulk of the Monocotyledons. 
At the back of the bay is a fine polished section of a buttress 
from the base of the Tapang (Ahauria excelsa), the largest tree 
in Borneo, attaining a height of 250 feet. 
BayX. The last bay contains the Dicotyledons, characterised by a 
Dicotyledons. 0 f cotyledons and foliage leaves with an irregularly netted 
venation. Here also the arrangement of the vegetative parts of 
the plant is based on its differentiation into root, stem, and leaf. 
In the two wall-cases the upper series of specimens illustrates 
the leaf, its form, veining, duration, the characters of its stalk 
and stipules, its modification for special purposes, and its 
arrangement on the stem and in the bud. In the lower row 
the root and stem are similarly treated, and above are some 
anatomical drawings. 
In the central case the chief types of the flower with its 
parts, the fruit and the seed are exhibited. 
A small space at the end of the bay is assigned to Hairs, 
Prickles, and similar structures, which are divided into two 
classes — Trichomes, or hairs proper, in which only the outer 
cell-layer (epidermis) of an organ takes part ; and Emergences, 
in which tissues beneath the epidermis are also concerned. At 
the back of the bay is a large transverse section of the Karri tree 
{Eucalyptus diver sicolor) of Western Australia, which grows to 
a height of 400 feet. The tree, of which this is a section, was 
about 200 years old when cut down. 
The Introductory Collection of Minerals will be found in the 
gallery devoted to that department of the collection (see p. 54). 
