g6 
from Geraldton to Albany are composed very largely of Fora- 
minifera. The beach sands of the islands off Fremantle and ■ 
adjacent pai'ts of the coast are particularly rich in species of 
this order. 
Diatoms. — Diatom frustules are composed of hydrous silica 
(opal), a substance which is very resistant to the attacks of air 
and water. For this reason the frustules tend to collect in beds 
wherever diatoms are growing. They are exceedingly abundant 
in the vicinity of Perth, particularly at Wanneroo and Jandakot, 
where their remains form beds several feet in thickness in many 
swamps and lakes. Some of these deposits have been examined 
by myself from a geological and chemical standpoint, details 
being given in the Annual Report of the Geological Survey for 
1903. So far as 1 am aware none of the numerous species in the 
State have, been classified. 
The Wanneroo deposits are all apparently still in process of 
formation. The surrounding land is drift sand and the waters 
of the swamps, presumably on this account, are rich in silica 
and so favourable to the growth of diatoms. These grow in 
countless millions in the water, and their cell walls, together with 
a considerable proportion of organic matter derived from the pro- 
toplasm of the plants, accumulate in beds under it. It is only 
when the water has evaporated in the summer that the beds can 
be examined, and 1 have found the month of March the best for 
this purpose. At that season of the year, except after an un- 
usually wet winter, Lakes Joondalup, Mariginiup, Janclabup, 
Little Badgerup, and Gnangara are almost wholly free from surface 
water, thus permitting a close examination of the diatomaceous 
earth which tills them to a depth of several feet. Where this 
material is perfectly dry the organic matter in it is very in- 
flammable and is readily ignited by a bush fire. Once alight it 
will smoulder for months giving off a somewhat rank and very 
distinctive reek very like that of Irish peat. 
A little caution is necessary in examining these beds. When 
burnt and unwetted, the earth sometimes loses all cohesion and 
any attempt to walk on it would result in sinking to one’s knees 
or deeper in fine powdery dust at the bottom of which the earth 
may still be red hot and burning. When dry and unburnt, the 
earth is tough and will support almost any weight, it is then 
usually pale grey in colour and very light. On different swamps 
its appearance may be quite dillerent under such conditions. 
For example, on Lake Mariginiup it dries in thin curled up flakes, 
on Little Badgerup in massive roughly regular polyhedra. When 
partly dry the earth is usually black or dark brown in colour 
and of the consistency of thick jelly. It will then just bear with 
safety the weight of an ordinary person. When thoroughly wet 
it forms a most treacherous bog into which cattle sink without 
hope of withdrawing and which is equally dangerous to any 
