18 
Trmisactions of the Boyal Society of South Africa. 
(O— DESCEIPTION OF THE FOSSILS. 
GASTROPODA.* 
Family NATICIDiE. 
Genus GYEODES, Conrad, 1860. 
Journ. Acad. Nat. Sci. Philadelphia, 1860, new series, vol. 4, part 3, 
p. 289. 
Gyeodes manuanensis, n. sp. 
Plate VIIL, figs. 9, 10. 
Description. — Shell sub-globose large, robust; spire low, 
depressed in its summit region, composed of five or six moderately 
inflated volutions posteriorly flattened and excavated ; upper 
margins of whorls obtusely angulate and furnished with small, 
rather obscure nodulations ; body-whorl of considerable size, 
broader than high, and about five times the depth of the penulti- 
mate ; basal region occupied with a prominent, wide, and deeply 
excavated umbilical cavity, which is funnel-shaped and bordered 
above by a revolving obtuse carina and within by a second 
revolving ridge which is parallel with it ; the walls of the um- 
bilical cavity are ornamented with a crowded series of obliquely 
curved longitudinal striations, whilst the remaining surface of the 
shell is covered with numerous prominent lines of growth curving 
obliquely from the suture over the shoulders of the whorls and 
extending to the basal margin ; there are no spiral striations ; 
aperture perpendicular, elliptical ; shell structure of moderate 
thickness. 
Dimensions. — 
Height 40 mm. 
Breadth 40 ,, 
Diameter of aperture — 30 x 15 mm. 
Observations. — The specimen described, of which there is, only 
one example, is apparently of adult growth, and beyond a few 
fractures in the neighbourhood of the mouth is remarkably well 
preserved, a fair amount of the original shell structure being still 
intact. It forms a good illustration of Conrad's Gyrodes (type 
= Natica petrosa of Morton from the Cretaceous of the United States), 
* The genera of both the Gastropod and Pelesypod groups of Mollusca mostly 
follow the order of Pelseneer's classification, as suggested in the A7in. Soc. Roy. 
Malac. Belgique, 1894, vol. 27, pp. 31-243. 
