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Ylll.— Remarks on some Fossil and Recent Shells, collected by Captain Bay- 

 field, R.N., in Canada. 



By CHARLES LYELL, Esq., V.P.G.S., F.R.S. 



[Read April 24, 1839.] 

 Plate XVI. 



Several eminent conchologists have observed, that in some strata of the En- 

 glish crag there are certain species and genera of shells which seem to indicate a 

 somewhat colder climate than that which now prevails in our latitudes ; and it has 

 been supposed that a similar inference may be deduced with still greater certainty 

 from the abundant occurrence of many arctic species in the most modern of the 

 marine Newer Pliocene strata of Scotland and Ireland. These opinions induce me 

 to offer some remarks on a collection of fossil and recent shells which have lately 

 been sent to me from Canada by Captain Bayfield, who procured the fossils from 

 the newest tertiary deposits bordering the Gulf of St. Lawrence, and the recent 

 Testacea from the Gulf itself. 



The shells were found principally at Beauport, on the east bank of a river of that 

 name, which enters the St. Lawrence on its northern side about two miles below 

 Quebec, in lat. 47° ; but the same formation is traced in the valley of the St. 

 Charles and many other places, at heights varying from 30 to 300 feet above the 

 Gulf. 



" The strata," says Captain Bayfield, " are of sand, gravel, and stiflF blue clay, similar to deposits at 

 present forming lower down, as well as higher up, the St. Lawrence. They fill a valley previously formed 

 in an ancient horizontal limestone, containing Trilobites, Orthocerata, &c. Angular fragments of this 

 limestone, and a Trilobite washed out of its matrix, were found amongst the modern shells. The upper 

 stratum of sand is nearly 1 00 feet above the St. Lawrence, and is almost exclusively composed of bivalves. 

 The strata have been traced a mile up the valley on the east bank of the Beauport river, the ancient 

 limestone forming the west bank. Similar shells were also met with, at a still higher elevation, on the 

 north side of the valley of the St. Charles, about three miles from Beauport. In these and all other 

 localities of the same formation, the lowest strata usually consist of clay, and the uppermost of sand and 

 clay mixed. It is in these last that the shells are abundant, being rare in the stiff blue clay. 



