128 SUPPLEMENT TO THE CRAG MOLLUSCA. 
small piece has broken out of the hinge. It is from the Middle Glacial sand of Hopton, | 
and, like most of the specimens in that sand, is worn. 
Lucina BorEALIS. Crag Moll., vol. 1, p. 139, Tab. XII, fig. 1 ; Supplement, Tab. IX, 
fig. 5. . 
Localities. Cor. Crag passim. Red Crag passim. Fluvio-marine Crag passim. 
Chillesford Bed, Chillesford, Bramerton, Aldeby, Easton, and Horstead. Lower Glacial, 
Weybourne (Reeve). Middle Glacial, Hopton and Billockby. 
This species is exceedingly common in the Cor. and Red Crags, as also in the Middle 
Glacial Sands at Hopton, but in this latter it is generally in a fragmentary condition, 
the only perfect valves that have occurred from these sands being those of very young 
shells. 
The shell figured in this ‘Supplement’ (Tab. IX, fig. 5) is of a specimen sent to me 
by Messrs. Crowfoot and Dowson, who found it at Aldeby. In form it strongly 
resembles L. spinifera, but I believe it is merely a distorted specimen of L. borealis. 
Dirtoponta pinatata, 8S. Wood. Crag Moll., vol. ui, p. 145, Tab. XII, fig. 5. 
Localities. As in ‘ Crag Mollusca.’ 
This was so called from a presumption that it was specifically distinct from rotundata, 
which I still believe it to be. I also, in the ‘ Crag Mollusca,’ placed D. dilatata, Sow.., 
from the older tertiaries of Sussex, as a synonym; and gave as another synonym the 
shell figured by Nyst under the name of D. dilatata, Phil. ‘The shell figured by 
Philippi under this name was, however, referred by him in a subsequent volume to 
D. rotundata (‘ Phil.,’ vol. ii, p. 24); while the shell figured by Nyst, and referred by 
him to Philippi’s so-called dlatata, is now called by Nyst D. Wood, apparently under 
the impression that Philippi’s d/atata is a subsisting species, instead of its being 
the same as D. rotundata. Nyst’s figure (‘Coq. Foss. de Belg., pl. 7, fig. 1) 
corresponds with the Crag shell, but his description, “son coté postéricur est tres elargé et 
subanguleux,’’ does not. My shell is also, I now believe, distinct from D. dilatata, 
Sow., of Dixon’s ‘ Geology of Sussex.’ The nearest approach to it that I know is a shell 
from Grignon (D. profunda, Desh.), but that is also, I believe, distinct. | Under these 
circumstances I have retained the Crag shell under the original name given by me to it in 
1840, although it is placed by the author of the ‘ Brit. Conch.’ as a variety only of rotundata. 
D. dilatata is given by the late Dr. S. P. Woodward in his list of Norwich Crag shells, but 
there is no authority attached to this name (unfortunately there are but few authorities for 
names in that list), and I am not certain whether the species he speaks of be the 
rotundata of Mont., or dilatata, 8. Wood. 
