Mr. D. Sharpe on Secondary Fossils from South Africa. 193 



Description of Fossils from the Secondary Rocks of Sunday River and Zwartkop 

 River, South Africa, collected by Dr. Atherstone and A. G. Bain, Esq. By 

 D. Sharpe, Esq., F.R.S., Pres. G.S. &c. 



[Plates XXII. XXIII. XXVIII.] 



Pinna Atherstoni, Sharpe. PI. XXII. fig. 1 . 



P. testa brevi, triangular!, subarcuata, longitudinaliter costata et medio angulata, antice sub- 

 quadrata : costis numerosis inaequalibus, undulatis ; lineis concentricis irregularibus decussatis. 



Shell triangular, short, slightly curved, with a longitudinal keel below the middle 

 of each valve, which is more prominent anteriorly, giving the anterior end of the 

 shell arhomboidal section : valves covered with numerous unequal, slightly waving, 

 longitudinal ribs ; crossed by undulating, irregular lines of growth. 



Length 4^ inches ; breadth 2^ inches ; thickness i-j inch. 



From Sunday River ; found at C. Roe's drift, in a grit with fragments of shells 

 and wood. 



This Pinna is nearly related to P. Hartmanni of Zieten, Goldf. t. 127. fig. 3, 

 which occurs in the Lias of Wiirtemberg. 



Fig. 1 a, side view ; fig. 1 b, transverse section of the anterior part. 



Modiola Bainii, Sharpe. PI. XXII. figs. 2 & 3. 



M. testa transversim elongata, subrecta, concentrice costata : costis medio divisis. 



Shell transversely elongated, with the back straight and the ventral edge very 

 slightly curved : ornamented with numerous concentric ribs, which are sloping and 

 very strong near the back, but divide into two or three branches before reaching 

 the middle of the valves ; these reunite on the lateral transverse keel and then 

 continue small and parallel to the ventral margin. The umbo not having been 

 seen, the proportions of the shell cannot be accurately ascertained ; the length 

 was probably more than eight times the breadth. 



From Sunday River ; found at C. Roe's drift, in a grit with fragmentary shells 

 and wood. 



This elegant shell has some resemblance to M. plicata, Sow., of the Middle 

 Oolites ; but it is straighter, much more elongated, and more regularly ornamented. 



Fig. 2, fragment of a large specimen; fig. 3a, fragment of younger shell; 

 fig. 3 b, section of fig. 3 ft. 



Perna Atherstoni, Sharpe. PI. XXII. fig. 4. 



P. testa triangulari, subglabra : cardinis ligamenti foveis numerosis, confertis. 



Shell nearly triangular, smooth, anterior side sloping, posterior side rounded : 



2d2 



