6 CRETACEOUS LAMELLIBRANCHIA. 
Deseription.—Shell thin, greatly elongated, compressed; the anterior part 
short and rounded; the posterior part very long and tapering, with a slight carina 
extending from the umbo to the postero-ventral angle, cutting off a flattened 
area. Umbones small. Ventral margin slightly sinuous posteriorly (except in 
young specimens, in which the posterior part of the valve is less produced) ; 
postero-dorsal nearly straight. Posterior margin truncated. Surface glossy, with 
very fine concentric lines. Margin entire. Teeth very numerous, minute, short. 
Adductor impressions faintly marked. 
Measurements : 
(1) 2) (3) (4) 
Length F 26 5 20 : 14 : 10 mm. 
Height : 3) ; 7 : 5 : Anh ae 
Affinities. —N. solea is more elongated than any other Cretaceous species here 
described (see page 1). 
T'ypes.—I have not seen the type;-it appears to be missing from the 
d’Orbigny Collection in the Museum of Natural History, Paris. Gardner’s 
specimens are in the British Museum. 
Distribution.—Lower Gault (zones ii, ii, v, vil) of Folkestone; Gault of 
Black Ven; Cambridge Greensand (jide Price). 
’ 
Nucurana Marta (d’Orbigny), 1844. Plate I, figs. 25 a—c, 26 a, b, 27. 
1844, Nucuta Manta, A. d’Orbigny. Pal. Frang. Terr. Crét., vol. iii, p. 169, 
pl. ceci, figs. 4—6. 
1850. Lrepa Mariam, A. d’Orbigny. Prodr. de Pal., vol. ii, p. 186. 
1866. — = F. J. Pictet and G. Campiche. Foss. du Terr. Crét. de Ste. 
Croix (Matér. Pal. Suisse, ser. 4), pt. 3, 
pp- 897, 401. 
1884. — — J. 8. Gardner, Quart. Journ. Geol. Soc., vol. xl, p. 188, 
pl. iui, figs. 28, 29. 
Description.—Shell elongated, inequilateral. Ventral margin considerably and 
evenly curved ; antero-dorsal straight or slightly convex, postero-dorsal slightly 
concave, both with a considerable ventral slope. Anterior end blunt and rounded ; 
posterior end pointed. Posterior part of shell more compressed than the median 
and anterior portions. Umbones pointed. Surface ornamented with numerous 
fine, concentric ribs, which are absent or indistinct on the anterior and posterior 
parts of the valves. Anterior teeth about thirteen, posterior more. 
Measurements : 
(1) (2) (3) 
Length 8 7 ; . 4mm. 
Height 5 4, é ete ates 
Thickness 3°5 -- — 
3° 
