51. Yellowish-grey flint passing into hornstone, in irregularly angular pieces, with brown glossy corroded surface. “La Saila; hills of silex and opal.”
52. White hornstone; a boulder with corroded glossy surface. “Strewed in large quantities between Wady el Beny and Wilkna, and on the summit of gypsum hills.”
53. Yellowish-white substance intermediate between hornstone and calcedony, in angular pieces, with cream-coloured cacholong on the surface. “On the way from Gatrone to Tegerhy.”
54. Brownish-red carnelian; a fragment, with irregularly botryoidal yellowish decomposed surface. From ditto.
55. Several fragments of variously shaped rough sand tubes; internal surface highly glazed. “From the sands near Dibla.”
56. Lithomarge, reddish-brown, here and there variegated with bluish-green and greyish, in fragments with rather tuberculated surface. “Aghadem, beds in the sandstone.”
57. The same, but penetrated by iron ochre, and much harder; with small imbedded pyriform concretions. From ditto.
58. Brownish-red and yellowish-grey variegated slaty clay, very soft and unctuous to the touch. From ditto.
59. Small-foliated amorphous gypsum, confusedly crystallized, with adhering red marl. “From the curiously formed gypsum hills of Bonjem to Hormut and Takui, with large quantities of opal on the top.”
60. Some specimens of white, granular, and foliated gypsum; one of the varieties composed of wedge-shaped laminæ. Bonjem.