8 CRETACEOUS LAMELL1BRANCHIA. 



(d'Orbigny). For the relation of this to N. scapha (d'Orbigny) and N. phaseolina 

 (Michelin), see pp. 4, 9. 



Remarks. — Specimens referred to JV. scapha (d'Orbigny) by Gardner {vide 

 ante, p. 4), and stated to come from the Lower Greensand of Atherfield, 

 probably belong to this species. One example is figured on PL I, fig. 32. 



Types. — The types, and also the specimens figured by Gardner, are in the 

 Bristol Museum. 



Distribution. — Blackdown Greensand (zone x ) ; Greensand of Haldon {fide 

 Downes) ; Grey Chalk of Dover {fide Gardner). 



Nuculana angulata {Sowerby), 1824. Plate I, figs. 33 a— c, 34 a, b, 35 a — d. 



1824. Nucula angulata, J. de C. Sowerly. Min. Concb., vol. v, p. 120, 



pi. cccclxxvi, fig. 5. 

 1850. Leda angulata, A. d'Orbigny. Prodr. de Pal., vol. ii, p. 159. 

 1854. — —J. Morris. Cat. Brit. Poss., ed. 2, p. 205. 



1866. — — F. J. Pictet and G. Campiche. Poss. du Terr. Cret. de 



Ste. Croix (Mater. Pal. Suisse, ser. 4), 

 pt. 3, p. 401. 

 1884. — — J. S. Gardner. Quart. Jouru. Geol. Soc, vol. xl, p. 138, 



pi. iv, figs. 17—19. 



Description. — Shell small, more or less oval or triangular, moderately convex ; 



somewhat rounded anteriorly, pointed posteriorly. Ventral margin regularly 



curved, but slightly sinuous posteriorly. Umbones prominent, incurved; a ridge 



extends from each umbo both anteriorly and posteriorly, limiting two depressed 



areas. Ornamentation consists of fine concentric ribs. Anterior and posterior 



portions of the hinge-line of nearly equal length ; teeth narrow, elongate. 



Measurements : 



(i) (2) (3) 



Length . . 5'5 .5 .4 mm. 



Height . . 4 3'5 . 3 „ 



Thickness .3 .3 . 2'2 „ 



(2) is one of Sowerby's types. 

 Affinities. — This species is similar to N. Marise (d'Orbigny), but is smaller, 

 more convex, with the posterior part of the shell usually less elongated, and 

 the umbones more prominent. 



Types. — In the British Museum. The specimens figured by Gardner are in 

 the Bristol Museum. 



Dish ibution. — Blackdown Greensand. 



