298 Annals of the South African Museum. 



a regular curve. Antero-dorsal margin rather longer than the 

 postero-dorsal. 



Ornamentation consists of numerous fine radial furrows. Near 

 the median part of the valve the furrows are nearly straight and 

 often discontinuous ; they are separated by broad, flat interspaces 

 on which fine concentric lines may occur. On the anterior and 

 posterior parts of the valve the furrows become more curved, 

 deeper, and more continuous, and the interspaces become narrower, 

 more raised, and rib-like. The furrows do not show punctae. 



Anterior ear large, with its anterior margin nearly at right angles 

 to the hinge-line, ornamented with fine ridges parallel with the 

 anterior margin; byssal sinus of moderate size. Posterior ear smaller 

 than the anterior, with its outer angle obtuse, ornamented with fine 

 radial ribs and growth-ridges. 



Left valve with ornamentation similar to, but rather coarser than, 

 that on the right valve. Anterior ear large with its outer angle 

 nearly rectangular. Posterior ear smaller than the anterior, with 

 its outer angle obtuse. 



Length 17 mm. ; height 19 mm. 



Affi.iiities. — -This belongs to the same type as P. virgatus, Nilsson,=*= 

 but appears to differ from the Swedish form in its finer ornamenta- 

 tion. In that respect it differs also from the forms from the 

 Ariyalur and Trichinopoli Groups figured by Stoliczkat as P. 

 curvatus, Geinitz. The Pondoland form appears to approach 

 most nearly the example from Texas figured by RomerJ as 

 P. virgatus. 



Sub-genus NEITHEA, Drouet. 



Pecten (Neithea) quinquecostatus, Sowerby.§ 



Plate XXXV., fig. 14. 



Several examples of this widely distributed species have been 



found, and seem to agree in every respect with European specimens. 



They are perfectly preserved and show clearly the fine, regular 



concentric ridges. || In some cases the small transverse denticles 



are present in the hinge of the right valve. 



* Petrific. Suecana (1827), p. 22, pi. ix., fig. 15. Hennig, Revision Lamell. i. 

 Nilsson's Petrific. Suecana (1897), p. 41, pi. ii., figs. 28, 33; pi. iii., figs. 32, 33. 



t Cret. Fauna S. India (1871), p. 433, pi. xxxi., figs. 15, 16; pi. xli., 

 figs. 4-G. 



+ Kreidebild. v. Texas (1852), p. 66, pi. viii., fig. 5. 



§ For synonymy see Woods, Mon. Cret. Lamell. England, vol. i. (1903), p. 202, 



II Woods, ibid., pi. xl., tigs. 1, 2c, 4b. 



