1 88 Bulletin 29 352 



Pecte?i Thompsoni, n. sp. 

 Plate 34, Figures 9, 10 



Shell thin, delicate, translucent, suborbicular, flattened, in- 

 equivalve; ribs eighteen or nineteen, rounded, a little wider than 

 the interspaces, giving a characteristically fluted aspect to the 

 valves; ribs and interspaces smooth except for very fine, raised, 

 concentric growth striae; right valve exceedingly flattened with 

 prominent ears, the anterior noticeably reflexed, deeply notched 

 beneath and sculptured with about five radial riblets more or less 

 squamose, especially that bordering the dorsal margin; a deep 

 sulcus marks the junction of the ear with the umbonal region; 

 posterior ear smaller, sub-triangular, its surface smooth except 

 for concentric growth striae similar to those on the face of the 

 valve; left valve also compressed but gently convex in the umbon- 

 al region ; ears more nearly equal, the anterior with four to six 

 radial threads and fine growth striae; the posterior smooth except 

 for the striae. An average-sized sized right valve measures in 

 length 20, altitude 18, semi-diameter 2; a left valve 18 X 17X3 

 mm. This species is readily distinguished by its flattened form, 

 discrepant valves, and large, twisted right ear. 



I take the greatest pleasure in naming this striking and 

 graceful Pecten in honor of Dr. G. B. Thompson of Bizara, Pon- 

 doland East, South Africa, whose devotion to the advancement 

 of the knowledge of the Cretaceous forms has been shown by his 

 collections, made under most difficult circumstances along the 

 wild and uninhabited coast of Pondoland. 



Locality. — (Exp'd'16) Bluff 3, Cercado de Mao. (Abund- 

 ant and characteristic). 



Pecten cercadica, n. sp. 



Plate 34, Figure 11 



Shell fan-shaped, moderately convex, fairly thick but trans- 

 lucent, nearly equilateral, whether equivalve or not I do not 

 know as we found but one valve; surface sculptured with sixteen 

 rounded, radial ribs with narrower interspaces; ribs and inter- 



