24 CRETACEOUS LAMELLIBRANCHIA. 
very near the posterior end. Lunule elongate, much depressed, sharply limited. 
Surface with lines of growth. Margins entire. Anterior part of hinge-line with 
about eighteen teeth, posterior part with seven. 
Measurements : 
(1) (2) (3) (4) (5) 
Length . : slash 7 0 =) 29) sma. 
Height . : 5 tO) 3) CCH 5 nue Ys ag 10 wags 
Thickness. —— : == 5 wey 5 27s) 5 Zire) op 
Affinities.—This species is distinguished from N. obtusa, Sowerby, and N. ovata, 
Mantell, by the sharply defined lunule and the angular posterior extremity ; it is 
also a smaller form. 
N. apiculata, Sowerby (Plate IV, fig. 8), from Blackdown, appears to me 
to be only a variety of N. dimpressa ; it is somewhat shorter in proportion to its 
height than the ordinary forms of N. impressa, and consequently has a more 
rounded outline. Sowerby’s diagnosis of N. apiculata is ** Convex, smooth, trans- 
versely obovate; posterior extremity pointed.” A specimen in the Museum of 
the Geological Society of London (No. 1564, Fitton Collection) is, 1 believe, the 
type, but is a little smaller than Sowerby’s figure. The only other example known 
to me is in Mr. Meyer’s Collection. The late Rev. W. Downes’ considered JN. 
apiculata to be a synonym of N. antiquata, Sowerby; but that species is more 
triangular in outline, the valves are much more convex, and the umbones more 
prominent. 
Types.—One of the types (Sowerby’s lower figure) is in the British Museum. 
One of the specimens figured by Gardner (fig. 12) is in the Bristol Museum; I 
have not seen the others; they are stated to be in the Rev. W. Downes’ Collection, 
now in the Exeter Museum. 
Distribution.—Blackdown Greensand. 
Nucuta aLBensis, d’Orbigny, 1844. Plate IV, figs. 9a, b, 10, 11, 12 a, b, 13 a, b, 
TAG nb. Va, Oy liGsse aid. 
1844. Nucuta atpensts, A. d’Orbigny. Pal. Frang. Terr. Crét., vol. iii, p. 172, 
pl. ccci, figs. 16—17. 
1850. — — — Prodr. de Pal., vol. ii, p. 187. 
1866. — — F. J. Pictet and G. Campiche. Foss. du Terr. Crét. de 
Ste. Croix (Matér. Pal. Suisse, ser. 4), pt. 3, pp. 411, 
417, pl. exxix, fig. 11. 
1884. — — J.S. Gardner. Quart. Journ. Geol. Soc., vol. x], p. 128, 
pl. in, figs. 6—8 ; pl. iv, figs. 24, 25. 
1 «Trans. Dey. Assoc.,’ vol. xii (1880), p. 436; and ‘Quart. Journ. Geol. Soe.,’ vol. xxxviii 
(1882), p. 88. 
