Coming to Ordovician rocks, the limestones of the Upper Finke Basin in South Australia contain _Orthis leviensis_ and _O. dichotomalis_. The Victorian mudstone at Heathcote may be of Ordovician age or even older; it has afforded a limited fauna of brachiopods and trilobites, amongst the former being various species of _Orthis_, _Chonetes_, and _Siphonotreta_. The latter genus is represented in both the Lower and Upper Ordovician rocks of slaty character in Victoria (Fig. 85 B). =Silurian Brachiopods.--= The Silurian system in Australasia as in Europe, N. America and elsewhere, is very rich in brachiopod life. It is impossible to enumerate even all the genera in a limited work like the present, the most typical only being mentioned. In New Zealand the palaeozoic fauna is at present imperfectly worked out, but the following genera from the Wangapekian (Silurian) have been identified, viz., _Chonetes_, _Stricklandinia_, _Orthis_, _Wilsonia_, _Atrypa_, and _Spirifer_. The specific identification of these forms with European types is still open to question, but the species are undoubtedly closely allied to some of those from Great Britain and Scandinavia. The Victorian Silurian Brachiopods are represented by the horny-shelled _Lingula_, the conical _Orbiculoidea_, a large species of _Siphonotreta_, _Stropheodonta_ (with toothed hinge-line), _Strophonella_, _Chonetes_ (with hollow spines projecting from the ventral valve, one of the species _C. melbournensis_ being characteristic of the Melbournian division of Silurian rocks), _Orthis_, _Pentamerus_, _Camarotoechia_, _Rhynchotrema_, _Wilsonia_, _Atrypa_ (represented by the world-wide _A. reticularis_), _Spirifer_ and _Nucleospira_ (Figs. 85, 86). New South Wales has a very similar assemblage of genera; whilst Tasmania possesses _Camarotoechia_, _Stropheodonta_ and _Orthis_. =Devonian Brachiopods.--= The Devonian limestones and associated strata are fairly rich in Brachiopods. The Victorian rocks of this age at Bindi and Buchan contain genera such as _Chonetes_ (_C. australis_), _Spirifer_ (_S. yassensis_ and _S. howitti_) and _Athyris_. In New South Wales we again meet with _Spirifer yassensis_, veritable shell-banks of this species occurring in the neighbourhood of Yass, associated with a species of _Chonetes_ (_C. culleni_) (Fig. 86 D, E). [Illustration: =Fig. 86--SILURIAN and DEVONIAN BRACHIOPODS.= A--Camarotoechia decemplicata, Sow. Silurian. Victoria B--Nucleospira australis, McCoy. Silurian. Victoria C--Atrypa reticularis, L. sp. Silurian. Victoria D--Chonetes culleni, Dun. Mid. Devonian. New South Wales E--Spirifer yassensis, de Koninck. Devonian. New South Wales and Victoria ] In the Upper Devonian of New South Wales abundant remains occur of both _Spirifer disjunctus_ and _Camarotoechia pleurodon_ (var.).