102 THE VICTORIAN NATURALIST 
species and young, and also of different parasites that attack them ; 
and will be glad to show them at the close of the meeting, to any 
one who may be interested in the subject. 
I regret that opportunities have not occured to allow me to work 
on this subject more continuously and thoroughly, so that I could 
have given more comprehensive details upon their life history. I 
feel that I owe an apology to the Club for its incompletenes, but, 
considering the importance of Economic Entomology in all is 
branches, I decided to bring it before you as a contribution toward 
a better knowledge of this tranch of practical science. 
GEOLOGICAL SKETCH OF SOUTH-WESTERN 
VICTORIA. 
By Joun Dennant. Part 1. 
( Continued.) 
The intrusive rocks are probably much older than those at the 
Chetwynd, and differ altogether in appearance and composition. The 
Wando rocks are almost a serpentine, of a marked green color, giving 
on analysis but 43 per cent. of silica, with as much as 30 per cent 
of magnesia, while the dykes of the Chetwynd and elsewhere are 
of a wholly different and much more acid character. 
When the slates are the surface rock, the soil is very poor, but as 
in many cases they are surrounded or overlaid by other formations, 
more or less denuded, great variations in the fertility of the land are 
observed. Along the valleys of the Glenelg and Wando, where the 
underlying primitive rock is concealed by thin patches of secondary 
strata, a very rich soil is produced. Opposite Roseneath, the junction 
of the slates with this last named formation is visible, and what is 
more interesting still, a few chains distant, shells of tertiary age ean 
be gathered from a band of limestone overlying the mesozoie beds. 
The secondary rocks are an outlier of the lignite-bearing strata of the 
Wannon district, and the limestone is directly connected with the 
immense area of the tertiaries to the westward. 
Although I close my remarks on this formation without being 
able to define its precise place in the geological series, there can be 
no doubt of its being the oldest in this part of Victoria, possessing 
perhaps greater points of resemblance to Lower than to Upper 
Silurian, notably in its high dip and generally perfeet cleavage. 
It certainly underlies the Grampian sandstone group, for granting 
that this does not now extend much beyond Mount Dundas, yet 
evidence is not wanting to show that at one time it had a much 
wider range ; even in the vicinity of the slaty beds just described, 
remnants of it can still be recognised, insignificant in extent, but of 
