66 Bibliographical Notices. 
differences between the species described by Jeffreys in his second 
volume and those of Forbes and Hanley :— 
Species added. Species excluded. 
Argiope decollata, Chemn. Hypothyris psittacea, Chemn. 
capsula, Jef. Anomia aculeata, Mill. 
Pecten Testze, Bivona. striata, Lov. 
Lima Sarsii, Lov. Pecten niveus, Macg. 
elliptica, Jeffr. Nucula radiata, F. & H. 
Limopsis aurita, Brocchi. Astarte ellipticas Brown. 
Arca obliqua, Phil. crebricostata, Forbes. 
Lepton sulcatulum, Jef. arctica, Gray. 
Axinus Croulinensis, Jef. Mactra elliptica, Brown. 
Cardium papillosum, Poli. Tellina proxima, Brown. 
Three of the additions made to our fauna—Argiope decollata, 
Lepton sulcatulum, and Cardium papillosum—are Mediterranean 
species, which have hitherto only occurred in the extreme south of 
the British Islands, off Guernsey; on the other hand, Lima Sarsit, 
Arca obliqua, and perhaps Limopsis aurita are Scandinavian forms 
which have now been met with in Shetland; while the four remain- 
ing shells have more extended range on our coasts. 
The especial attention which has been paid of late years by geo- 
logists to the more recent deposits of our islands, and especially to 
those contemporaneous with and subsequent to the glacial epoch, 
has led to a great advance in knowledge respecting the connexion of 
our present fauna with that of the latest periods of geological time ; 
nor have these investigations been confined to the land. The dredge 
has made known to us the fact that on the sea-bottom all round our 
shores there are lying, mixed with the dead and living examples of 
our present fauna, the shells of various Mollusca, often remarkably 
fresh in appearance, which have apparently ceased to live in our 
waters. It is often a matter of extreme difficulty to determine 
whether a species dredged only in a dead state be recent or fossil ; 
and hence it happens that Hypothyris psittacea, Astarte crebri- 
costata, A. arctica, and Tellina proxima, together with Mya Udde- 
valensis, Margarita cinerea, Margarita (Skenea) costulata, Natica 
elausa, Astyris Holbdllii, Trophon scalariformis, &c., have been in- 
troduced among our Mollusca, but are now believed to be extinct 
representatives of more northern existing species, which once lived 
associated with our recent Mollusca, but gradually died out as the 
temperature of the waters which surround our coasts increased, and 
are now no longer to be found living in a latitude so far south. 
Most conchologists will also be ready to acquiesce in the suppres- 
sion of Anomia aculeata and A. striata as distinct from A. ephip- 
pium and A. patelliformis; but what shall we say to Pecten niveus 
being merged in P. varius, Nucula radiata in N. nucleus, Astarte 
elliptica in A. suleata, and Mactra elliptica in M. solida? In 
writing on the first of these changes, Mr. Jeffreys says :—‘‘I fear 
that some of my conchological friends will be terribly shocked at my 
