168 Annals of the South African Museum. 



the beak is moderately pointed, and the lateral slopes are inclined at 

 about 75-80° ; the surface is concentrically striated. 



Dimensions. — Length 13*5 mm. ; width 12 mm. 



Locality. — (No. 121) Top of Hottentots' Kloof. 



Order NEOTREMATA. 

 Family DISCINID^. 



OEBICULOIDEA BAINI (Morris and Sharpe). 

 (Plate XX., figs. 4, 5.) 



1846. Orbicnla Bainii, Morris and Sharpe, Quart. Journ. Geol. 



Soc, vol. ii., p. 277, pi. x., fig. 5. 

 1856. Orbicula Bainii, Sharpe, Trans. Geol. Soc, ser. 2, vol. vii., 



p. 210, pi. xxvi., figs. 20-23. 

 1893. Discina Baini, Von Ammon, Zeitschr. Gesell. Erdkiinde 



Berlin, Bd. xxviii., p. 359, fig. 4. 

 1897. Orhiculoidea baini, Schuchert, Syn. Amer. Foss. Brach. 



(Bull. U.S. Geol. Surv., No. 87), p. 277. 



This species was first described from the Falkland Islands by 

 Morris and Sharpe, and subsequently from South Africa by Sharpe. 

 Eecently Von Ammon has described it from Matto Grosso, Brazil. 

 The shape of the examples (Nos. 158, 159) in the present collection 

 is circular ; the brachial valve is moderately conical, being elevated 

 to a height equal to about one-third the diameter ; the beak is 

 excentric, being distant about one-third or one-fourth the diameter 

 from the posterior border. The pedicle valve is slightly concave ; 

 the pedicle opening is large, oval, and depressed, and is connected by 

 a narrow slit with the posterior margin, from which it is distant 

 about one-third or one-fourth the diameter of the shell. 



Dimensions. — Diameter 20-24 mm. 



Affinities. — In the allied species Orb. humilis Hall," from the 

 Marcellus-Hamilton beds of North America the beak of the brachial 

 valve is more subcentral. Kayser + describes a species as Orb. cf. 

 humilis Hall, from the Argentine Devonian. 



Localities. — (No. 158) North of Whupperthal. (No. 159) Gamka 

 Poort. 



* Hall, Palffiont. N.Y., vol. iv., 18G7, p. IG, pi. ii., fig. 18. 



t Kayser, Zeitschr. deut. Geol. Gesell., Bd. xlix., 1897, p. 302. 



