Mr. D. Sharpe on Secondary Fossils from South Africa. 197 



sharp ribs: 15 to 25 large ribs near the umbilicus, rising into spines, and then 

 each dividing into 3 or 4 smaller ribs, which cross over the rounded back : umbi- 

 licus narrow, deep, and well-defined : aperture semi-oval. 



The young shell only differs from the adult in having rather fewer ribs. 



Diameter of the figured specimen 5 inches ; width of opening 3^ inches ; height 

 of the last whorl 2^ inches. Some broken specimens in the collection indicate a 

 much larger size. 



Found at Sunday River ; some specimens occur in a crushed condition. A 

 fragment of a large individual^ of apparently the same species, is from the Zwart- 

 kop River. 



This Ammonite is related to A. macrocephalus, of the Middle Oolite of Europe, 

 and to A. Herveyi, of the Lower Oolite. Our specimens do not show the septa. 



Ammonites Bainii, Sharpe. PI. XXIII. fig. 2. 



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

 dorso rotundatis, 40-costatis: costis acutis, antrorsum subincurvis, ad latera 2-3 furcatis, 

 deinde super dorsum continuis : umbilico parvo, profundo : apertura semicirculari, interdum 

 contracta. 



Shell subglobose, with few inflated whorls ; ornamented with numerous, slightly 

 bent, siiarp ribs, about 15 in number near the umbilicus ; the ribs divide on each 

 side of the whorl into 2 or 3, which continue across the round back : umbilicus 

 narrow, deep, and well-defined : aperture semicircular, from time to time con- 

 tracted ; and the contractions marked by a stouter rib, projecting forward more 

 than the rest. 



Diameter 2 inches ; width of opening 1^ inch ; height of the last whorl f of an 

 inch. 



Found at Sunday River. 



With some general resemblance to A. Atherstoni, this species is not only 

 distinguished by having fewer ribs, but also by the periodical contractions of 

 the mouth, which connect it with A. Humphriesianus, A. Brackenridgii, and A. 

 linguiferus of the Lower Oolite of Europe. 



Gryphaa imbricata, Krauss, sp. PI. XXIII. fig. 3. 



Exogyra imbricata, Krauss, Acad. Nat. Cur. xxii. pi. 50. fig. 2. 



G. testa ovato-oblonga, crassissima, squamoso-rugosa : valva inferiori naviculari, apice 

 sinistrorsum incurvo, sulco laterali obsolete ; superiori concaviuscula, apice recurvo. 



Shell ovate-oblong, very thick, externally scaly, attached when young : lower 



