142 CRETACEOUS LAMELLIBRANCHIA. 
1887. Puicarura Barrorsi, A. Peron. Hist. du Terr. de Craie (Bull. Soc. Sci. 
Hist. Nat. de l’Yonne, ser. 3, vol. xii), 
p. 167, pl. ui, figs. 5—7. 
1889. — noposa, A. Fritsch. Stud. im Gebiete der bdhm. Kreideformat. 
IV. Die Teplitz. Schicht, p. 86, fig. 83. 
1895. — ef. Noposa, B. Lundgren. Mollusk. i Mammitll.-och Mucron- 
zonerna i nordéstra Skane (K. Svenska Vet.- 
Akad. Handl., n. s., vol. xxvi, No. 6), p. 41. 
1897. = Barroisi, H. Woods. Quart. Journ. Geol. Soc., vol. li, p. 388, 
pl. xxvii, figs. 18, 19. 
Deseription.—Shell small, ovate, rounded, alittle oblique. Right valve inflated, 
with the apical part truncated by the attached surface, which is often fairly large. 
Left. valve flattened or slightly concave, often with a subcircular opening near 
the umbo. Both valves ornamented with more or less numerous, strong, nearly 
smooth and rounded ribs, separated by deep and well-marked grooves; the ribs 
may bifurcate near the margins of the valves, and new ribs may be intercalated. 
Strongly marked growth-lines occur at intervals, and also concentric lamelle, the 
latter being most distinct on the left valve. 
Measurements : 
(1) (2) (3) (4) 
Length . : : : 575 ay) 50 4-5 mim. 
Height . F : ; 6:0 6:0 Bra) BB) op 
(1—4) from the Chalk Rock, near Winchester. 
Remarks.—This species was described and figured by Reuss as P. pectinoides, 
Sowerby, but it differs greatly from Sowerby’s species. D’Orbigny referred it to 
P. nodosa, Dujardin ;' Geinitz and Fritsch followed the same course. Barrois, 
although using the name P. nodosa, stated that Dujardin’s figure was very 
incomplete, and consequently his specimens could not be identified as belonging 
definitely to that species. Peron subsequently pointed out that the species under 
consideration differs considerably from P. nodosa, Dujardin; the latter bemg about 
four times larger, more elevated, and ornamented with large, simple, widely 
separated ribs. He therefore described and figured it as a new species— 
P. Barvroist. 
T'ypes.—Reuss’s specimens came from the Pliner-Kalk and Pyrope Sand of 
Trziblitz, and from the Pliner-Mergel of Weberschan. Peron’s figured specimens 
came from the Upper Turonian of Valmy. 
Distribution.—Zone of R. Cuviert of the Devon coast. Zone of VT. gracilis of 
the Devon coast and Dover. Zone of H. planus of Dover, the Sussex coast, 
Twyford (Winchester), ete. Chalk Rock of Winchester, etc. Zone of M. cor- 
1 «Mém. Soe. gdol. de France,’ vol. 11 (1837), p. 228, pl. xv, fig. 14. 
