72 SUPPLEMENT TO THE CRAG MOLLUSCA. 
Rissoa pximta? Jeffreys. Supplement, Tab. VII, fig. 5. 
RissOA EXIMIA, Jeff. Ann. and Mag. Nat. Hist., n. s., vol. iv, p. 299, 1849. 
CHEMNITZIA EXIMIA, Forb. and Hanl. Brit. Moll., vol. iv, p. 278, pl. xe, fig. 1, as 
Rissoa eximia. 
Opostomia EXIMIA, Jeff. Brit. Conch., vol. iv, p. 155, pl. Ixxv, fig. 4. 
Localities. Coralline Crag, Sutton. Living, Shetland Seas. 
The single specimen of this shell, which is represented in the figure as above, is all 
that I have yet met with, and was found by myself in the Coralline Crag of Sutton. Itis 
strongly ribbed, and has three somewhat broad spiral strize on the lower part of the whorl, 
in which respect there is a slight accuracy in the figure which shows but two such striz. 
These striz crossing the ribs give rise to two rows of depressions or cavities between 
them. ‘The specimen is slightly worn. 
Rissoa semicosrata, Woodward (non Mont.). Crag Moll., vol. 1, p. 102, Tab. XI, 
fig. 10, and also fig. 9 (as 2. pulchella). 
Localities. Red Crag, Butley, Sutton, and Kesgrave. Middle Glacial, Billockby. 
This shell was described by Woodward in his ‘ Geology of Norfolk ’ (1833) under the 
name of 7urbosemicostatus, auctorum, but the authors of the ‘ British Mollusca’ and the author 
of the‘ British Conchology’ agree that Moniagu’s Zurbo semicostatus is identical with 2. striata 
of Adams. As, however, I consider the Crag fossil to be distinct from any known recent 
species, I have retained it under the name of semzcostata, Woodward, that name being 
unoccupied now that Adams’ older name of s¢r/atais applied to the other (Montagu’s) shell ; 
the synonym Zwrbo semicostatus, Mont., given at page 102 of ‘ Crag Moll.,” being an error. 
His son, Dr. Woodward, in the list of Norwich Crag shells m White’s Directory of 
Norfolk, refers this species to czconspicua, Alder ; but the Crag forms invariably have the 
outer lip thickened and dentated within, which the recent cmconspicua has not ; and if 
this be a specific character, the two shells must be distinct. 
My identification of the shell shown in fig. 9, of Tab. XI, of Crag Moll., with 
pulchella, Phil., has been dissented from; and in such dissent I agree, as I now believe 
it to be the same as semzcostata, Woodward ; I therefore unite these species under the 
name of semicostata. Since the publication of the ‘Crag Moll.’ I have obtained three 
specimens of the original semzcostata, Woodward (fig. 10 of Tab. XI), from the Red Crag 
of Butley, which may be synchronous with the Fluvio-marme Crag of Bramerton, 
from which the shell shown in fig. 10 came. Those figured as pulchella (fig. 9, a, 6) 
were, from what I consider to be, an older portion of the Red Crag, viz. that at Kesgrave 
