114 SUPPLEMENT TO THE CRAG MOLLUSCA. 
exterior. Our present shell’ seems intermediate between nucleus, which is more extended 
posteriorly, and prozima. 
Nucuna TENUIS, Mont. Crag Moll., vol. ui, p. 84, Tab. X, fig. 5. 
Localities. Red Crag, Bawdsey. Fluvio-marine Crag, Bramerton (Reeve). Chilles- 
ford bed, Chillesford, Bramerton (2eeve), and Aldeby (Crowfoot § Dowson). Middle 
Glacial, Hopton? Upper Glacial, Bridlington. 
I have seen the specimens from all the above localities. Those from Hopton are 
fragmentary and may belong to xwcleus, but more probably to the present species. 
Lepa opnoncorpss, S. Wood. Crag Moll., vol. ii, p.90,Tab. X, fig. 17 (as Leda myalis, 
Couth.). 
NucuLa osLoncorpEs, S. Wood. Mag. Nat. Hist., New. Ser., vol. iv, p. 297, tab. 14, 
fig. 4, 1840. 
Localities. Red Crag, Sutton and Butley, Fluvio-marine Crag, Bramerton, Thorpe, 
Bulchamp, Thorpe by Aldbro, and Yarn Hill.  Chillesford bed, Chillesford, Aldeby, 
Easton Cliff, Bramerton, Horstead, Coltishall, and Burgh. Lower Glacial, Belaugh, and 
Rackheath. Middle Glacial, Hopton and Billockby. 
The shell figured No. 17 in Tab. X of vol. ii of ‘Crag Moll.’ as Z. myalis, Couthouy, can, 
I think, hardly be referred to that species. It is the same as that figured No. 4 of tab. 14 of 
vol. iv of ‘ Mag. Nat. Hist.,’ New Series, to which I gave the name of od/ongoides. This shell 
is common in the newer part of the Red Crag (that of Butley) and in the Fluvio-marine 
Crag at Thorpe by Aldbro, Bulchamp, and Bramerton, and also in the Chillesford bed at 
all its localities, and in al! it maintains well its form and characters. I for some 
time thought it to be identical with the North East American shell, Amatula, Say, but it 
is less attenuated, and has not the preponderance in length of the hinder (or posterior) part 
of the shell over the anterior which characterises that species, and the ligamental socket 
is larger. It also approaches, in some respects, all of the following, viz. hyperborea, 
Torel ; amygdalea, Valenciennes ; sapotilla, Gould; myalis, Couth.; and Woodwardi, 
Hanley, which, perhaps, are all varieties of one species; but I cannot satisfactorily 
identify it with any of them, though it seems to come nearest to Ayperborea. I 
have, therefore, fallen back upon my original name odlongoides. The figure in the 
‘Ann. and Mag. of Nat. Hist.’ is a most accurate representation of it. The shell 
occurs in the Lower Glacial sands of Belaugh and Rackheath, and fragments (some- 
times large) of what seems to be the same species are very common in the Middle 
