60 Transactions of the Boyal Society of South Africa, 
however, of greater thickness, more robust, and exhibiting a 
rounded margin in the antero-ventral region instead of a sUght 
concavity ; in addition the valves are more convex. G. dentata 
has been recognised by Dr. G. Miiller in the Neocomian beds of East 
Africa (Bornhardt, Deutsch.-Ost-Afrika," 1900, vol. 7, pi 24, figs. 
8, 9, p. 548), and a further specimen of doubtful determination has 
been described by Mr. E. Etheridge from the Umsinene Kiver 
deposits of Zululand (Anderson, " Third and Einal Eeport Geol. Surv. 
Natal and Zululand," 1907, pi. 1, figs. 13-15, p. 73), which, moreover, 
is badly preserved and difficult to recognise from the illustrations ; 
the author in this case speaks of its general resemblance to G. avicu- 
loides of J. de C. Sower by and G. anceijs of Orbigny. 
It is interesting to note that so far as can be ascertained, these 
elongate forms of Gervillia are quite unknown in the Cretaceous 
beds of Northern Africa. 
G. suhlanccolata appears to range geologically from the Barremian 
to the Albian {Schloeiibachia rostrata zone), and is more characteristic 
of British than foreign localities. 
Locality. — North end of False Bay. 
Family OSTEEID^. 
Genus OSTEEA, Linn^us, 1758. 
Systema Naturae, 1758, edition x., p. 696. 
OSTEEA ZULULANDIiE, sp. UOV. 
Plate II., figs. 1-5. 
Description. — Shell of small size with elongate, narrow and 
moderately shallow valves, the lower being of crescentic shape. 
The ligamental region is curved and acuminate, whilst the inner 
margins of the dorsal half of the valves are usually dentated ; the 
anterior border of the lower valve is deep, abrupt and concave, and 
its surface is marked by concentric growth-lines which are crossed 
by a few obscure, distant and radial plications. The upper valve 
has a squarish outline at its commencement, besides possessing a 
fringed or dentated border. 
Dimensions (of two lower valves). — 
Large form. Small form. 
Length 34 20 mm. 
Height 15 14 „ 
Observations. — This oyster is of abundant occurrence in the rocks 
of this region, although mostly in a fragmentary condition. The 
lower valves are those more frequently preserved, the upper being 
