207 
NUCULA levigata. 
TAB. CXCII.---Figs. 1 and 2. 
Spec. Cuar. ‘Transversely elliptical, convex, 
smooth ; posterior side truncated; edge en- 
tire. 
Neaxty related to N. Cobboldie, but wider and per- 
fectly smooth: it has not even the striae beneath the 
surface, so usual in other species. The lunette is im- 
pressed, convex, oblong, and occupies the truncated 
part of the pesterior side; it has a pit or compressed 
tooth in the hinge, similar to several other species. 
Of this I have received fragments from Mrs. Cobbold, 
which were very pearly, although found in the Crag of 
Holywells. The perfect specimens represented are from 
Woodbridge ; they are of the usual colour of ihe Crag, 
but still betray the once more pearly internal coat. They 
are nearly as perfect as living specimens; I was glad 
to see them ; they were favoured by Mr. Parkinson. 
NUCULA similis. 
TAB. CXCII.---Figs. 3, 4, and 10. 
Syn. Arca Nucleus. Brander, p. 40. f. 101. 
Brocchi, IT. 480? 
Nucula margaritacea. Lamarck Env. de 
Paris, 193°? 
Spec. Cuar. ‘Transversely obovate, depressed, ob- 
scurely striated longitudinally ; posterior side 
straight ; lunette imbedded ; concave in the 
middle, oblong ; edge crenulated. 
Tus differs from the recent British Nucula (Arca nu- 
cleus, Linn.) in the angle formed by the two lines of hinge 
