208 Mr. D. Sharpe on Palaozoic Fossils from South Africa. 



Shell nearly hemispherical, ribbed : ventral valve nearly flat, with the edges a 

 little depressed ; dorsal valve convex : both valves ornamented with fourteen to 

 sixteen prominent, rounded, simple ribs, radiating from the umbo to the margin, 

 and nearly equal in width to the rounded furrows between them. Hinge-line nearly 

 straight, shorter than the breadth of the shell, which is rounded oflf at the extre- 

 mities of the back. 



Length f of an inch ; breadth 1 inch. 



Found abundantly as casts in a ferruginous rock, together with casts of Stropho- 

 mena Bainii and Encrinital joints, in the Cold Bokkeveld, Orthis palmata occurs 

 also (with Homalonotus and Tentaculites) in the dark schists of the Warm Bokke- 

 veld ; with Conularia in the Cedarberg ; in the light-coloured schists of Hottentots 

 Kloof; and (with Encrinites) in a light-coloured schist from Kokman's Kloof, pre- 

 sented to the Geological Society's Museum by Major Colebrooke. 



It has been also found in the Falkland Islands by Mr. C. Darwin. 



Fig. 7, exterior of the ventral valve, from a gutta-percha mould of an impression 

 of the shell ; fig. 8, exterior of the dorsal valve, from a gutta-percha mould of an 

 impression of the shell ; fig. 9, interior of the ventral valve ; fig. 10, interior of the 

 dorsal valve. 



Terehratula Bainii, Sharpe. PI. XXVI. figs. 1 1 & 12. 

 T. testa ovata, sublaevi, concentrice rugata ; valva dorsali convex^, ventrali subdepressa. 



Shell ovate, nearly smooth, with a few deep concentric wrinkles ; dorsal valve 

 elevated ; ventral valve slightly convex. 



Length 1 inch ; breadth | of an inch ; thickness about fths of an inch. 



Found plentifully as casts in a dark-grey siliceous rock, in the Warm Bokkeveld, 

 together with casts of Spirifers and of Orthis palmata. 



The specimens of this species in Mr. Bain's collection are all more or less 

 crushed, and do not afford good materials for defining the species. 



Fig. 11, exterior of tbe ventral valve, from a gutta-percha mould of an impres- 

 sion of the shell ; fig. 12 a, cast of the interior of the ventral valve ; fig. 12 b, cast 

 of the interior of the dorsal valve. 



Strophomena Bainii, Sharpe. PI. XXVI. figs. 13 & 17. 



S. testa transversim semi-ovata, depressa, subtiliter radiata : radiis numerosis simplicibus, 

 alternatim minoribus ; ad marginem 120-130: linea cardinali recta, valvarum latitudinem 

 aequante. 



Shell transversely semi-oval, depressed, covered on both valves with numerous, 

 fine, simple rays, increasing in number as the shell enlarges by the insertion of 

 smaller rays between the others, until they reach the number of 120 or 130 at the 



