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SUPPLEMENT TO THE CRAG MOLLUSCA. 



exterior. Our present shell seems intermediate between nucleus, which is more extended 

 posteriorly, and proximo, . 



Nucula tenuis, Mont. Crag Moll., vol. ii, p. 84, Tab. X, fig. 5. 



Localities. Red Crag, Bawdsey. Fluvio-marine Crag, Bramerton {Reeve). Chines- 

 ford bed, Chillesford, Bramerton (Reeve), and Aldeby (Crowfoot 8r 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 nucleus, but more probably to the present species. 



Leda oblongoides, S. Wood. Crag Moll., vol. ii, p.90,Tab. X, fig. 17 (as Leda myalis, 



Couth.). 



Nucula oblongoides, 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, Belangh, and 

 Rackheath. Middle Glacial, Hopton and Billockby. 



The shell figured No. 17 in Tab. X of vol. ii of 'Crag Moll.' as L. 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 oblongoides. 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 all it maintains well its form and characters. I for some 

 time thought it to be identical with the North East American shell, limatula, 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 hyperborea. I 

 have, therefore, fallen back upon my original name oblongoides. 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 



