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



portions, thinner anteriorly : valves traversed by numerous concentric lines, which 

 are nearly obsolete in the middle of the shell, but rugose on the posterior side. 

 On the left valve the anterior lateral tooth is nearly obsolete. 



Length 1^ inch ; breadth 1^ inch ; thickness f of an inch. 



Found at Sunday River, in greenish shelly grit. 



Fig. 9 a, exterior of the left valve ; fig. 9 b, hinge of the left valve : the posterior 

 tooth has been partially broken away. 



Area Aiherstoni, Sharpe. PI. XXII. fig. 10. 



A . testa trapezoidal! ; anticebrevi; medio depressa ; postice elongata, oblique truncata, pli- 

 cata : costis minutis numerosis radiantibus, lineis concentricis decussatis. 



Shell trapezoidal ; short anteriorly ; with a broad depression down the middle, 

 bounded by a broad, rounded, transverse keel ; obliquely sloping posteriorly : the 

 anterior and middle portions of the valves are ornamented with numerous fine 

 radiating lines, crossed by irregular lines of growth : the sloping posterior portion 

 is divided into three obliquely-longitudinal furrows. 



Length f ths of an inch ; breadth f ths. 



Found at Sunday River, in a shelly sand-rock. 



[Neither the radiating lines nor the posterior furrows are sufficiently shown in 

 the figure.] 



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



P. testa compressa^ ovali ; antice rotundata ; postice subcompressa : rugis concentricis inse- 

 qualibus. 



Shell oval, flatfish, regularly rounded anteriorly, slightly sloping on the posterior 

 dorsal side : valves crossed irregularly by unequal concentric ridges. 



Length f of an inch ; breadth 1^ inch ; thickness |ths of an inch. 



Found at Sunday River and near Enon, in a grit sometimes full of the casts of 

 the shell. 



Fig. lift, cast from the impression of the left valve ; figs. 11 6 & 1 1 c, two views 

 of a cast of the interior. 



The casts show the hinge to have had two strong teeth on the left valve and one 

 on the right valve, with a sharp edge extending laterally along the dorsal margin of 

 the valves on each side of the cardinal teeth. 



Ammonites Atherstoni, Sharpe. PI. XXIII. fig. I. 



A. testa subglobosa, costata : anfractibus paucis, rotundato-inflatis, lateribus 15-25-costatis, 

 dorso rotundatis multicostatis : costis rectis, acutis, ad latera 3-4-furcatis, deinde super dorsum 

 continuis : umbilico parvo, profundo : apertura semi-ovali. 



Shell subglobose, with few inflated whorls, ornamented with numerous straight 



