186 
that the evidence of the fossils is rather indefinite. The beds are cer¬ 
tainly Bendigonian and not Castlemanian. Number 1900 is Didymo grap¬ 
tus nitidus. This is common in the Castlemaine series, but is not found 
throughout the Bendigo series. How far down into the latter rocks it 
passes is as yet unknown, but its presence in the present collection is 
evidence that we are not dealing with the lowest members of the Bendi¬ 
gonian. 
In such a small and imperfect collection of specimens, negative evi¬ 
dence is not of very great value, but as no “ tuning-fork ” graptolites are 
present, there is no sign that the uppermost Bendigonian is represented. 
1 should not then feel justified in saying more than that the rocks are 
Bendigonian, but do not belong to the lowest members of the series. 
[Report sent in 5.9.07.] 
The Age. of the Rocks About Dunolly. 
The determination of the relative ages of rocks by means of fossils 
rests on so sure a foundation as to need no defence, and graptolites yield 
to no other group of organisms in the exactness with which they may be 
utilized for this purpose. Though not absolutely confined to Ordovician 
and Silurian rocks, they here attain their greatest profusion, both in 
numbers and in species, and the shortness of the range in time of many 
easily recognised forms enables us to determine with certainty the relative 
age of the containing rocks. 
The graptolites of the central area of Bendigo have been fairly well 
studied, and we now know that rocks of the same age, or Bendigonian, 
occur in many other places in the State. The most characteristic fossils 
are Tetragraptus fruticosus , Tetragraptus pendens , and Goniograptus 
thureaui. Tetragraptus approximate is shown by a study of this area 
to be characteristic of the lowest part of the Bendigo- series, and to pass 
into the older rocks below, while Tetragraptus serra, Tetragraptus bryo- 
noides , and Phyllograptus typus range throughout, but also pass up into 
the higher series of beds. 
Below the Bendigo series is found a series of rocks which are best 
studied at Lancefield, and are hence called Lancefieldian. They are 
characterized by profusely and often irregularly branching graptolites, 
such as Bryo graptus Victoria , which seems to range up into the Bendi¬ 
gonian, though it is there extremely rare. Several species of Clonograptus 
occur, such as C. plexitis , C. rigidus, and C. rigidus var. tenellus. The 
gigantic C. magnificus is common at many localities, and passes up into 
Lower Bendigonian. Dictyonema is represented by two stoutly-built 
forms, D. macgillivrayi being the largest species known. 
The district treated of more particularly in this report extends from 
Bendigo westward nearly to Bealiba, a distance of close upon 40 miles, 
and from near Maryborough northward to Inglewood, a distance of about 
2=; miles. 
Scattered over this area are some forty localities from which grapto- 
lites have been obtained. The material for the most part has been in an 
extremely poor state of preservation, so that in a large number of cases 
it was not possible to determine the fossils; still, from most localities a 
sufficient number of identifications w r ere made to fix the age of the beds 
approximately. Had the material been better it might have been possible 
to subdivide the rocks more closely and to add to our knowledge of the 
fauna of the period. But this could not be done. 
