88 Annals of the South African Museum. 



cutting off a narrow, flattened, or slightly concave area contiguous 

 with the cardinal margin. The greatest inflation occurs at about the 

 middle of the valve. 



The surface bears numerous closely spaced, delicate, raised, con- 

 centric linear ornaments, very weakly developed and indistinct in 

 the umbonal part of the shell, more strongly developed in the 

 inferior half of the valve. These linear ornaments are not produced 

 with perfect regularity, but show occasional inequalities in their 

 spacing, and an occasional coalescence of adjacent lines may be 

 observed, particularly in the posterior part of the valve. 



Dimensions. 



Length 17 mm. 



Greatest height 11 ,, 



Greatest depth of a single valve 5 ,, 



Occurrence. Found by Mr. Eogers in a wash-out 100 feet above 

 Coega station, at a point one mile north of Coega Hotel (441g). 



Remarks. The specimen described has both valves in position, 

 and is perfect except posteriorly. When the above description was 

 written the right valve was quite perfect, though the lunular region 

 (in this genus posterior to the umbo) was somewhat obscured by 

 very hard matrix, but an attempt to remove this resulted in slight 

 injury to the valve at the posterior border, so that the margin there 

 is now not quite perfect. Unfortunately a single specimen only was 

 obtained', but it seems to be sufficiently well preserved and well 

 characterised to support the establishment of a new species. 



The shell is distinguished by its oval form and rounded, soft out- 

 lines. In these respects it bears a considerable resemblance to 

 Nucula obtusa J. de C. Sow., from the Upper Greensand and Black- 

 down Beds of England.* 



GENUS GEAMMATODON F. B. Meek and F. V. Hayden. 



GEAMMATODON JONESI (Tate). 



Plate II., figs. 14, 14a. 

 1867. Area (Cucull&a?) jonesi E. Tate, Quart. Journ. Geol. Soc., 



vol. xxiii., p. 161, pi. ix., fig. 9. 



Occurrence. Collected by Miss M. Wilman at Coega. This shell 

 is also recorded by Messrs. Eogers and Schwarz as occurring in the 

 highest of three beds of sandstone on the Grass Eidge road near 

 Uitenhage.f The specimens described by Tate occurred " in a 



* Woods (3), vol. i., p. 22, pi. iv., figs. 2, 3, 4 (1899). 

 t Rogers and Schwarz (1), p. 9. 



