200 PEocEEDiNGS or THE GEOLOGICAL sociETr. [Jan. 11, 



Per cent. 



British 59-3 



Southern 37-0 



Arctic 100-0 



N. E. American 90-7 



N. Pacific 18-5 



My friend Mr. Eobert Dawson of Cruden, who has explored the 

 malacology of the Aberdeenshire coast with great success, tells me 

 that when dredging he finds a great many semifossil Arctic shells 

 belonging to species which he never meets with alive. These he 

 supposes (and, I think, with great probabiUty) to be derived from 

 glacial beds passing underneath the sea, and extending for a con- 

 siderable distance out from the coast. He has kindly furnished me 

 with the following list of these shells, in reference to which he 

 Bays, " All the fossils included in the list were dredged by me off the 

 coasts of Cruden and Slains, at a distance of from three to eight 

 miles from land, and at the depth of from 30 to 45 fathoms. As, 

 however, some of them {TropJion scalariformis and Gunneri, Pecten 

 Islandicus, &c.) have been brought up by the fishermens' lines at 

 the distance of thirty miles from land, I believe that the fossil-deposit, 

 whatever it may be, extends to a great distance seaward. The 

 reason why they are not found nearer land appears evidently to be 

 that the sea-bottom, for at least three miles from shore, consists 

 of fine sand, covering probably the fossil- deposit beneath. None of 

 these species have been found by me alive ; and from the appear- 

 ance of aU the specimens, I believe that none of them are alive in 

 this district." 



No. 



Species. 





Astarte boreahs, Chemn 



Astarte sulcata, var. elliptica 



Astyris (Columbella) Holbollii, Bech ( = Mangeha 



HolboUii, Moller) 



Cardium exiguum, Crmelin (=C. pygmseum, F.SfS.) 

 Corbula gibba, Olivi (=C. nucleus, Lam. 8f JF. Sf H.) 

 Cyclostrema costulatum, Morch (=Skenea? costu- 



lata, i?'. ^S.) 



Lepeta caeca, Milller (= Patella cerea, Moller) . . 

 Margarita striata, JBrod. ^ Sow. (=M, ciaerea, 



Couthouy) 



Mesalia? borealis, BeoTc ( = Scalaria Eschrichti, 



Moller) 



Mya truncata, var. UddevaUensis 



Natica affinis, Gnielin (=N. clausa) 



Natica Islandica, Omelin (=N.helicoides,-F. 8f H.) 



