91 
Age Affinities of the Fauna. 
The trilobites and brachiopods possibly afford the best evidence as 
to the relative age of the Knowsley beds at Heathcote. Amongst the 
former group Dinesus is perhaps the commonest genus, but its relation¬ 
ship to other known genera is not very clear. It has been compared 
with Lloydia, a form apparently more closely allied to Solenopleura than to 
Bathyurus, the former genus ranging through Cambrian and Ordovician. 
In this series NotasapJius occurs fairly abundantly as regards the pygidial 
portion, whilst cranidia are not infrequent, and one exceptionally good 
specimen is now figured. The genus is almost essentially of an Upper 
Cambrian type, and is closely related to Dorypyge , from which it differs 
chiefly in the expanding glabella and the less strongly marked side furrows. 
The pygidia in both genera are almost identical. In view of this close 
relationship it is interesting to note that Dorijpyge is regarded by Walcott, 
who has described at length the relationships of the Chinese trilobite faunas, 
to typify the Middle Cambrian series. 1 Saratogia appears to be represented 
in the Heathcote fauna by an Upper Cambrian form, which elsewhere is 
found in the Potsdam formation of North America. The cranidia referred 
provisionally to Saukia seem also related to an Upper Cambrian species. The 
occurrence here of Agnostus australiensis is valuable evidence of age, having 
regard to its previous discovery in the Upper Cambrian limestone of the 
Dolodrook River, N.E. G-ippsland. 
Of the ten genera of brachiopods recorded from this fauna five are 
typically Cambrian, viz., Lingulella, Acrothele, Billingsella, Eodrthis, and 
Huenella. Three are Cambrian genera, ranging into the Ordovician, viz., 
Obolus, Acrothele , and Billingsella (dying out in L. Ordovician). Those 
purely of Ordovician aspect are Leptobolus, Hebertella, Eostrophomena (basal 
Ordovician), and Clitambonites . Six genera extend down to Middle Cambrian 
and older, viz., Obolus, Lingulella (throughout), Acrothele (throughout), 
Billingsella (throughout), Eodrthis (Middle Cambrian to Lower Ordovician), 
and Huenella (Middle and Upper Cambrian). Thus it will be seen that the 
balance of the forms represented point to a Cambrian facies. 
Of the other genera, Grammysia does not seem to have been recorded from 
beds older than the Trenton Series (Lower Ordovician), so that assuming 
the present form to belong to this genus its range is now extended. 
The branchiopod, Lepeditta, occurs in the Cambrian of North America. 
Regarding Protospongia, this seems to be restricted to the Cambrian 
elsewhere, the related genus Phormosella only being recorded from younger 
(Silurian) beds. In South Australia Protospongia is a' Lower Cambrian 
fossil. 
The thallophyte, Sphenothallus, was previously known only from the 
Upper Ordovician (Hudson River Group). 
Summing up this evidence, the strongest factors in the fauna are those of 
the trilobites, which appear to show close Upper Cambrian affinities, and the 
brachiopods, as Lingulella, Acrothele, and Billingsella, of Cambrian age, as 
well as the branchiopod, Lepeditta. Less- common forms are those of 
Ordovician aspect, as Eostrophomena, Clitambonites , Grammysia, and 
Sphenothallus. So far as the present study goes it points to an Upper 
Cambrian horizon, the fauna having secondary affinities both with the Middle 
Cambrian and Lower, and even Upper Ordovician. It is therefore an 
extremely interesting case of a passage fauna with an admixture of forms 
that are of wide range in other localities. 
1 Smithsonian Wise. Colls., vol. LXIV., No. 1, 1914, pp. 64-65 et seq. 
