NUCULANA. 



Nuculana phaseolina (Michelin), 1836. Plate II, figs. 1 a—d, 2 a, b, 3. 



1836. Nucula phaseolina, H. Michelin. Mem. Soc. Geo!. France, vol. iii, 



p. 102, pi. xii, fig. 6. 

 1844. — subbecubva, A. d'Orbigny (non Phillips). Pal. Franc. Terr. 



Cret., vol. iii, p. 170, pi. ccci, figs. 7 — 11. 

 1850. Leda subbecubva, A. d'Orbigny. Prodr. de Pal., vol. ii, p. 136. 

 1866. — phaseolina, F. J. Pictet and G. Camiriclie. Fobs, du Terr. Cret. 



des Envir. de Ste. Croix (Mater. Pal. 

 Suisse, ser. 4), pt. 3, p. 401. 

 1S84. — — J. S. Gardner. Quart. Journ. Greol. Soc, vol. xl, 



p. 135, pi. iii, figs. 22—24 (pi. v, 

 figs. 26—29?). 



Description. — Shell oval, rather high, convex, nearly equilateral; anterior 

 extremity broadly rounded ; posterior somewhat pointed and slightly compressed ; 

 ventral margin nearly parallel to the dorsal. Umbones prominent. Lunule 

 indistinctly defined. Escutcheon oval, deep, not sharply limited posteriorly. 

 Surface ornamented with numerous fine, close-set, concentric ribs, which are 

 indistinct or absent on the posterior part of the shell; a few of the later ribs cut 

 the postero-ventral margin obliquely. 



Measurements : 



Length ...... 10'5 mm. 



Height 7 „ 



Thickness ...... 7 ,, 



Affinities. — This species is similar to N. lineata (Sowerby), but is more equi- 

 lateral, relatively shorter, more rounded at the extremities, and the ornamentation 

 is finer. 



Nuculana Neckeriana (Pictet and Roux) is larger and more convex than 

 N. phaseolina, and is apparently ornamented with lines of growth only. 



Remarks, — Michelin's figure and description are very unsatisfactory, and the 

 characters of his species can only be determined from the works of later writers 

 and from specimens in French collections. The average size of the French speci- 

 mens appears to be greater than that of the English. 



Types. — I have not seen the type. D'Orbigny's specimens are in the Museum 

 of Natural History, Paris. Gardner's specimens are in the British Museum. 



Distribution. — Lower Gault of Folkestone. 



