52 Transactions of the Boy a I Society of Sonth Africa. 
Chama conica, J. Sowerby, Mineral Conchology, 1813, vol. 1, pi. 26, 
fig. 3, pp. 69, 70. 
Chama plicata, ibid., pi. 26, fig. 4, p. 70. 
Exogyra conica, J. de C. Sowerby, Mineral Conchology, 1829, vol. 6, 
pi. 605, figs. 1-3, p. 219. 
Exogyra Icsvigata, J. de C. Sowerby, Mineral Conchology, 1829, 
vol. 6, pi. 605, fig. 4, p. 220. 
Exogyra conica, Goldfuss, Petrefacta Germanias, 1833, vol. 2, 
pi. 87, fig. 1, p. 36. 
Ostrea conica, Orbigny, Pal. Fran9aise, Terr. Cretaces, Lamelli- 
branchia, 1846, pi. 478, figs. 5-8, pi. 479, figs. 1-3, p. 726; 
Coquand, Geologie et Paleontologie Constantine, 1862, 
p. 293 ; Coquand, Monographie du Genre Ostrea Terrain 
Cretace, 1869, pi. 53, figs. 1-7, p. 150 ; Cotteau, Peron and 
Gauthier, Echinides Fossiles de I'Algerie, 1878, Fasc. 4, 
Cenomanian, pp. 18-57. 
Exogyra conica, Sequenza, Atti B. Accad. Lincei (Roma), 1882, 
Ser. 3, Mem. vol. 12, p. 176. 
Ostrea conica, Peron, Desc. Mollusques Cretaces, Explor. Scientif. 
Tunisie, 1891, part 2, pi. 23, figs. 8-10, p. 113. 
Exogyra conica, Jukes-Browne and Hill, Cretaceous Bocks of 
Britain, Gault, &c., Mem. Geol. Surv. United Kingdom, 1900, 
vol. i., p. 466 ; Cretaceous Eocks of Britain, Upper Chalk, Mem. 
Geol. Surv. United Kingdom, 1904, vol. 3, p. 475. 
Observations. — The specimens from the Manuan Creek district 
referred to this somewhat variable species, consist of five lower 
valves of small size associated with matrix exhibiting external 
features, and showing the typically arched form of the shell, with 
its high, curved, sub-angulate elevation. The posterior side is deep, 
abrupt, and more or less vertical, or gently sloping outwards, 
whereas the front area is excavated, depressed, and oblique. The 
surface is ornamented with irregularly arranged concentric growth- 
lines, and without any vestige of radial striations covering the 
umbonal region, such as are described and figured by Orbigny. 
This radial sculpture is not noticed in the original description, so 
that it was apparently unknown to the two Sowerbys, whose 
types were procured from the Blackdown beds, although indications 
of its presence may be sometimes seen in examples from the same 
deposits. Prof. Peron was unable to detect such a character in his 
Tunisian specimens, so it may be concluded that it is exceedingly 
rare, and confined only to very well-preserved shells. 
