The Cretaceous Fauna of Pondoland. 291 



author," may perhaps be related to N. natalensis, but the specimens 

 figured are not sufficiently perfect for comparison. 



This species is referred by Etheridge to the genus Latiarca, but it 

 differs from that in the absence of a raised margin to the posterior 

 adductor impression, and in being more nearly equilateral ; also the 

 anterior teeth are relatively shorter and the posterior teeth longer. 

 It differs from Grammatodon in having the anterior teeth nearly 

 parallel to the hinge margin and the posterior teeth relatively 

 shorter; in these characters it agrees with Nemodon. 



Bemarhs. — Twenty-one left valves, five right valves, and one 

 specimen with the valves united have been seen. The type is in 

 the British Museum. 



Genus PECTUNCULUS, Lamarck. 



Pectunculus africanus, Griesbach. 



Plate XXXIV., figs. 8-12. 



1871. Pectunculus africanus, Griesbach, Q.J.G.S. xxvii., p. 66, 



pi. iii., fig. 8. 



Description. — Shell rather small, more or less sub-quadrate but 

 rounded ; somewhat higher than long, the greatest length being 

 below the middle of the valve ; only slightly inequilateral, moderately 

 convex, with the postero-dorsal part compressed. Anterior margin 

 rounded. Dorsal part of posterior margin more or less truncate and 

 sometimes forming an obtuse angle with the part below which curves 

 and passes gradually into the ventral margin. Umbones small, 

 inconspicuous, only slightly curved. Hinge-line long, curving con- 

 siderably. In young specimens the outline of the shell is more 

 orbicular, the length and height are equal or nearly equal, and the 

 greatest length is at the middle of the valve. 



Ornamentation consists of numerous narrow, only slightly raised 

 radial ribs, separated by linear grooves. On the posterior half of 

 the valve the ornamentation is rather more distinct than on the 

 anterior half owing to some of the ribs being rather more prominent. 

 Between the prominent ribs one or two smaller ribs occur. Internal 

 margins of valves coarsely crenulate. 



Length 22 . 20 . 18-5 . 14 . 12 mm. 

 Height 23 . 21 . 20 . 14 . 13 ,, 



Affinities. — This species presents some resemblance to P. subauri- 



* Petrefakt. Kreideformat Insel. Sachalin. Mem. Acad. Imp. Sci. St. Petersb., 

 ser. 7, vol. xix., No. 3 (1873), p. 24, pi. v., fig. 6, pi. viii., figs. 6, 7. 



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