172 CRETACEOUS LAMELLIBRANCHIA. 
2? 1885. Preren ELonGatus, Ff. Nitling. Die Fauna d. baltisch. Cenoman. (Palae- 
ont. Abhandl., vol. ii), p. 20, pl. in, 
fio. 6. 
1887. — — A. Peron. Hist. du Terr. de Craie (Bull. Soe. Sci. 
hist. et nat. de ’Yonne, ser. 3, vol. xii), 
p- 163. 
1893. _— = R. Michael. Zeitschr. d. deutsch. geol. Gesellsch , 
vol. xly, p. 235. 
1895. os (Cutamys) ELonGATUS, FH. Tiessen. Ibid., vol. xlvii, p. 468. 
1896. —_ pLonaatus, A. J. Jukes-Browne and W. Hill. Quart. Journ, 
Geol. Soe., vol. li, 
p. 151. 
1900. = — Jukes-Browne. Cret. Rocks of Britain (Mem. Geol. 
Survey), vol. i, p. 451. 
Non 1833. —— — A. Goldfuss. Petref. Germ., vol. 1, p. 59, pl. xciv, 
Hee, Oe 
— 1844. = = F. M‘Coy. Carb, Limest. Foss. Ireland, p. 92, pl. xvi, 
fig. 9. 
— 1846. — comans, A. H. Reuss. Die Verstein. der bohm. Kreideformat., pt. 
2, p. 29, pl. xxxix, fig. 13. 
2. 18. 
ete., p. 441, pl. xvii, 
a — oBpLiquus, Reuss. Ibid., p. 29, pl. xxxix, fi 
—— heyy l. — mLoneatus, J. Phillips. Geol. Oxford, 
fio. 19. 
Description.—Shell ovate, pomted dorsally, higher than long, of little convexity, 
nearly equilateral. Ears rather large, very unequal. Apical angle from 78° to 
about 90°. 
Right valve flattened or shehtly convex, ornamented with numerous ribs, which 
are frequently grouped in triplets—a larger central rib with a smaller on each 
side—but sometimes occur in pairs or singly. The smaller ribs appear at varying 
distances from the umbo in different specimens. Each rib bears many lappet-like 
scaly projections placed transversely; these are sometimes close together and 
arranged very regularly, but may be more distant and somewhat irregular. In 
places fine growth-ridges are present. The grooves between the ribs are rather 
narrow and rounded. Narrow portions of the valves at the antero- and postero- 
dorsal margins are without ribs, but are covered by numerous fine grooves placed 
nearly perpendicularly to the plane of junction of the valves. Ears with radial ribs, 
which are often indistinct, and with well-marked growth-lines ; on the posterior ear 
strize (like those on the margin of the valve) are sometimes seen crossing the ribs ; 
anterior ear large with a deep sinus, posterior ear smaller, triangular. 
Left valve of moderate convexity with ornamentation similar to that of the right 
valve. Kars triangular, with many spiny ribs; the anterior larger than the 
posterior. 
