The Invertebrate Fauna of the Uitenhage Series. 77 



has, however, a very different aspect from that of Goldfuss ; it 

 apparently has a narrower apical angle, and the surface ornaments 

 are so delineated as to be scarcely comparable with those of P. 

 atherstoni. The resemblance of P. atherstoni to the Liassic form 

 usually known by Zieten's name is clearly a fact of no importance 

 in the question of the age of the Uitenhage fauna. It may be noted 

 that a specimen of Pinna from the Perna-bed of Atherfield, Isle of 

 Wight, preserved in the Sedgwick Museum at Cambridge, has form 

 and proportions closely similar to those of P. atherstoni. The 

 specimen is unfortunately ill-preserved and unfitted for a de- 

 tailed comparison. A similarly broad form has also been recorded 

 from the Buda Limestone, the upper part of the Lower Cretaceous 

 series of Texas.* 



GENUS OSTEEA Linnasus. 



OSTREA SP. 



Specimens of Ostrca (305, 306, 336) which occur in the cliff below 

 the old school-house at Dunbrodie (right bank of Sunday's River), 

 in association with Perna atherstoni, Pecten cottaldinus and Gastro- 

 cliCBiia dominicalis, are in a very poor state of preservation and 

 consist chiefly of fragments. Valves of flattened form measure 

 upwards of 40 mm. from the umbo to the opposite border and about 

 30 mm. from margin to margin in a direction perpendicular to this. 

 The outline of the valve becomes broadly pointed at the umbonal 

 end. Other imperfect individuals are represented by valves of 

 smaller dimensions, and these appear to be less elongated and more 

 convex. None of the valves suffices for specific determination, but 

 it is probable that two forms are represented. 



GENUS EXOGYEA T. Say. 



EXOGYRA IMBRICATA KraUSS. 



1843. Exogyra imbricata P. Krauss, Amtlicher Bericht iiber die 



zwanzigste Versammlung der Gesellsch. deutsch. 



Naturforscher und Aerzte zu Mainz im Sept., 1842, 



p. 129. 

 1850. Exogyra imbricata P. Krauss, Nov. Act. Acad. Caes. Leop.- 



Carol. Nat. Cur., vol. xxii., pt. 2, p. 460, Tab. 50, figs. 



2a-2d. 

 1856. Gryplicea imbricata D. Sharpe, Trans. Geol. Soc. Lond., 



ser. 2, vol. vii., p. 197, pi. xxiii., figs. 3a, 3b. 



* Shattuck (1), p. 19, pi. vii. 



