176 Annals of the South African Museum. 



specific name, and it is very doubtful whether they are correctly 

 referred to Odostomopsis abeihensis (Blanck.), but it is certain that 

 the Uitenhage form here ascribed with doubt to Natica cannot be 

 brought into close comparison with Whitfield's genus." 



GENUS ACT^EONINA A. d'Orbigny. 



ACT^EONINA ATHERSTONI (Sharpe). 



Plate VIII., figs. 15, 15a, 16, 160, 166. 



1856. Actaon atherstoni D. Sharpe, Trans. Geol. Soc. Lond., ser. 2, 



vol. vii., p. 200, pi. xxviii., fig. 19. 



Supplementary Descriptive Note. The shell consists of about six 

 whorls, in the last of which there is a tendency to develop a steeply 

 sloping and slightly convex shoulder below the suture, demarcated 

 from the flattened central portion of the whorl by an ill-defined, 

 blunt spiral ridge. The previous whorl also shows these characters, 

 though in less marked degree, but the earlier-formed whorls have 

 a more evenly rounded outline, most convex near the suture, more 

 flattened below. The whorls are ornamented over their whole 

 surface by numerous delicate, impressed, linear, spiral striae which 

 are crossed by more conspicuous furrows and rounded ridges of 

 accretion, most noticeable in the last whorl. The spiral angle 

 is about 45. 

 Dimensions. 



Height of a specimen with six whorls 19 mm. 



Greatest diameter of the last whorl 9 , , 



Height of the aperture 10 



Greatest width of the aperture 4*5 ,, 



Occurrence. Collected at Grass Eidge, three miles east-north-east 

 of Uitenhage (333), and from a clay-pit in the lower part of the 

 Marine Beds on the left bank of the Zwartkop's Eiver near Eawson 

 Bridge (343) ; also at Dunbrodie, Sunday's Eiver (283, 284). Speci- 

 mens from the South African Museum are from the Sunday's Eiver. 

 The record of occurrence given by Sharpe was " the lowest strata of 

 the Zwartkop crag." Mr. Rogers collected specimens of this form 

 in 1905 at the bare slope W. 30 S. from the middle of Barkly Bridge, 

 on the farm Olifant's Kop, Sunday's Eiver (24h) ; from the highest 

 beds in a kloof behind Colchester, Sunday's Eiver (499g) ; and from 

 a cliff W. 20 S. from Comley's house, right bank of Sunday's Eiver 

 (92h). From this last locality was also obtained a specimen (95h) 

 * Whitfield (1), p. 425. 



