iv INTRODUCTION. 
correspond with letters and numbers on the colored specimen labels, 
and thus indicate the exact spot on the map where each specimen 
was collected, and the formation it belongs to. The letters R., F., M., 
on the maps and labels, show whether the specimen is Rock, Fossil, 
or Mineral. 
Illustrative horizontal sections, similar to the one accompanying 
4 sheet 14 S.W., Maldon, will eventually be constructed for all the 
more interesting } sheets; and a system of lettering on the face 
of the map has been adopted, by which the student can easily 
ascertain the probable nature of the formations underlying those 
that occupy the surface (depicted by the color on the map) of any 
given area. The letter G. indicates Granite; C., Lower Silurian ; 
S., Upper Silurian; V., Volcanic; T., Tertiary, &c.; and the 
number attached to the letter indicates the probable mineral or 
lithological character of the rock. Thus, V1. on TP3. on Cl. 2 
indicates Volcanic formation (basalt) resting on Pliocene Tertiary 
gravel, or “lower gold drift,” on a bottom of Lower Silurian slate 
and sandstone. 
The arrangement of the specimens described in this Catalogue 
was planned and superintended by myself. The descriptions are 
the jomt work of myself and colleagues, Messrs. Ulrich, Aplin, 
Etheridge, and Taylor. The analyses, when not otherwise stated, 
have been made by Mr. J. Cosmo Newbery, Analyst to the Survey. 
ALFRED R. ©. SELWYN, 
Dir. Geo. Survey of Victoria. 
Geological Survey Office, 
May, 1868. 
