The Invertebrate Fauna of the Uitenhage Series. 25 



II. THE AGE OP THE FAUNA. 



(a) Summary of Previous Work. In 1837, Hausmann recorded 

 the occurrence of some shells obtained by Hertzog from strata in 

 the Sunday's Eiver district, to which he ascribed a Lower 

 Cretaceous age. These included a Hamites, which was compared 

 with H. intcrmedius J. Sow. and H. funatus Brongn., and a Trigonia 

 which was thought to resemble T. dadalea Park.* Goldfuss after- 

 wards described and figured two of Hausmann' s shells under the 

 names Lyrodon herzogi and Cytherea herzogi, and also considered 

 them to be of Greensand age.f 



The examination of a small collection of lamellibranchs obtained 

 by F. Krauss in 1839 from strata exposed on the Zwartkop's Eiver, 

 led that author to the conclusion that they indicated a Lower Green- 

 sand horizon,^ and in another paper Krauss furnished excellent 

 descriptions and figures of these shells, maintaining a similar view 

 concerning their age. 



In 1851 a collection of fossil plants and molluscs, obtained by 

 E. Eubidge on the Sunday's Eiver, was exhibited before the British 

 Association at Ipswich by Colonel Portlock, who remarked that the 

 shells were apparently of Jurassic age, while Dr. Harvey's examina- 

 tion of the plant remains was thought to corroborate this view.|| 



In his well-known paper published in 1856, A. G. BainU referred 

 the Uitenhage fossils with doubt to the Lias, basing this opinion 

 upon the prevalence of a supposed Liassic form, " Gryphcza incurva." 

 The shell mistaken for this, however, was Exogyra imbricata, pre- 

 viously described by Krauss, which, as we shall see, bears only a 

 superficial resemblance to the Gryphaa mentioned, and is in reality 

 closely comparable with certain Lower Cretaceous forms of Exogyra. 

 Appended to Bain's paper were D. Sharpe's descriptions of the 

 Secondary fossils collected by Atherstone and Bain from localities 

 on the Sunday's and Zwartkop's Eivers. The forms described, 

 principally Mullusca, led Sharpe to the conclusion that they most 

 nearly resembled European species of the Middle and Lower 

 Oolites ; he compared his Ammonites atherstoni with A. macro- 

 cephalus and A. herveyi, while believing Ammonites baini to be 

 related to A. humphresianus and other Lower Oolitic forms. 



* Hausmann (1), p. 1457. 



t Goldfuss (1), Band II., p. 202, pi. 137, fig. 5 (1837); p. 239, pi. 149, fig. 10 

 (1840). 



I Krauss (1), pp. 129, 130. Krauss (2). 



|| Portlock (1). U Bain (1). 



