212 CRETACEOUS LAMELLIBRANCHIA. 
Non. 1869. Janrra quapricostata, H. Favre. Moll. Foss. de la Craie de Lemberg, 
p. 155. 
— 1876. Voxa quapricosrara, D. Brauns. Senon. des Salzberges (Zeitschr. f. d. 
gesammt. Naturwiss., vol. xlvi), 
p. 388. 
— 1877. Janira quapricosrata, A. Peron. Bull. Soc. géol. de France, ser. 3, vol. v, 
p. 502. 
— 1889. Vota quapricostata, H, Holzapfel. Die Mollusk. Aachen. Kreide (Palzeon- 
tographica, vol. xxxv), p. 297, 
pl. xxvi, fig. 20. 
= = = = O. Griepenkerl. Senon. von Kénigslutter (Paleeont. 
Abhandl., vol. iv), p. 48. 
— 1892. Nurryea Quapricostara, K. Futterer. WKreidebild. des Lago di Santa 
Croce (Paleont. Abhandl., vol. 
vi), p. 80, pl. 1, fig. 6. 
— 1894. Vora quapricosrara, A. Hennig. Om Ahussandst. (Geol. Foren. i Stock- 
holm ForhandL., vol. xvi), p. 520. 
= = = — B. Lundgren. Mollusk-faunan i Mammillat. och 
Mucronata zonerna (IK. Svenska 
Vet.-Akad. Handl., N. F., vol. 
xxvi, No. 6), p. 44. 
— 1895. — a F. Vogel. Hollindisch. Kreide, p. 25. 
— 1896. = == A. Rutot. Bull. Soe. Belge de Géol., ete., vol. x, 
p- 00. 
— 1901. — — H. Imkeller. VWreidebild. am Stallauer Eck, ete. 
(Palwontographica, vol. xlvii), 
p. 31, pl. i, figs. 8, 9, 
Description—Shell large, ovate, rounded ventrally, more or less pointed 
dorsally, nearly equilateral; postero-dorsal a little longer than the antero-dorsal 
margin. Hinge-line long; ears large. 
Right valve convex. Umbo prominent, meurved. Length of valve either 
equal to or slightly less than its height; greatest length at about the middle of 
the valve. Usually with twenty-one (occasionally twenty-four) ribs, which curve 
shehtly outwards; all are strong and rounded, with slightly narrower furrows 
separating them. Six of the ribs are rather larger than the others, and project 
slightly at the ventral margin, forming angles, between which the margin of the 
valve is straight or shghtly concave. The interspaces between the six main ribs 
are flattened, and in each, three (rarely four) smaller ribs occur; these are of 
nearly equal size, but the middle is sometimes shghtly larger than the lateral. 
Occasionally this regularity im the ribs is partly lost owing to the stronger ribs 
being more numerous and the smaller ribs fewer than usual. Both ribs and 
furrows are crossed by numerous, very fine, regular concentric ridges, which 
are continued on to the areas. Antero- and postero-dorsal areas of fairly large 
size and sloping outwards—the former a little smaller than the latter. Antero- 
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