48 Transactions of the Boijal Society of South Africa. 
Natural casts of Baily's expansus also frequently show obscure, 
elevated, radial striations proceeding from the umbonal area to the 
ventral margin, clearly proving the presence of corresponding 
markings on the inner surface of the valve. 
Associated with this specimen in the same rock are CucnllcEa sjj., 
Semifusns sp., and fragmentary Baculites (see p. 96), which closely 
resemble B. hailyi of Mr. H. Woods from the Campanian rocks of 
Pondoland [Ann. South African Museum, 1906, vol. 4, part 7, pi. 44, 
fig. 5, p. 341, which includes B. sulcatus {pars) of Baily, Quart. 
Journ. Geol. Soc, 1855, vol. xi., pi. xi., figs. 5a and 5h, non 5c, p. 457). 
Locality. — Umkwelane Hill. 
Genus GEEVILLIA, Defrance, 1820. 
Dictionnaire des Sciences Naturelles, 1820, vol. 18, p. 502. 
Gervillia sublanceolata, Orbigny. 
Plate III., figs. 7-10. 
Gervillia aviculoides, J. de C. Sowerby, Mineral Conchology, 1826, 
vol. 6, pi. 511, figs. 1, 2, 3, 5 {non 4), p. 16 {non Perna aviculoides, 
J. Sowerby, 1814). 
Avicula lanceolata, E. Forbes, Quart. Journ. Geol. Soc, 1845, vol. 1, 
pi. 3, fig. 8, p. 247 {non J. de C. Sowerby, 1826). 
Avicula sublanceolata, Orbigny, Prodrome Paleontologie, 1850, 
vol. 2, p. 119. 
Gervillia alpina, Pictet and Eoux, Desc. Moll. Foss. Gres Yerts 
Geneve, 1853, pi. 41, fig. 3, p. 496. 
Gervillia anceps, Pictet and Eenevier, Desc. Foss. Terr. Aptien St. 
Croix — Mat. Pal. Suisse, 1858, Ser. 1, pi. 17, p. 121 {non 
Deshayes, 1842). 
Gervillia alpina, Pictet and Eoux, Desc. Foss. Terr. Cretace St. 
Croix — Mat. Pal. Suisse, 1869, ser. 5, pi. 155, figs. 2-4, p. 83. 
Gervillia sublanceolata, H. Woods, Cretaceous Lamellibranchia of 
England, Mon. Pal. Soc, 1905, pi. 10, figs. 14-16, pi. 11, fig. 1. 
Text figures 7, 8, p. 74. 
Observations. — The species here determined is represented by four 
excellent fragments, three of which probably belonged to an indi- 
vidual with a possible antero-posterior measurement of about 170 
millimetres. Parts of both valves exhibit details of the hinge region : 
the oblong ligament cavities being more or less equidistant, and of 
narrower contour anteriorly, whilst lying beneath these is a pair of 
elongate, well-elevated, ridge-like teeth, diverging slightly from the 
anterior extremity and continuing in a posterior direction almost 
