Of the Vicinity of Mo7itreaL 409 



as Rhynconella psittacea and Pecten Islandicus, and those con- 

 taining Saxicava rugosa and other h'ttoral shells. It is also ob- 

 servable that the shells occurring at Beauport and not at Mon- 

 treal, are more of an oceanic character than those of the latter 

 locality ; and this may, perhaps, be connected with the vicinity 

 of the open sea at Quebec. Sir W. E. Logan informs me that 

 the Beauport locality seems to be at the entrance of an ancient 

 inlet. This would account for a mixture of shore and sea shells. 

 "We may next direct our attention to the shore limits of the 

 waters in which the shells of our one hundred feet level lived. It 

 Is evident that if in a given locality a bed occurs containing deep 

 sea shells, say indicating depths of 20 to 50 fathoms, and anotber 

 containing littoral shells, we must suppose that the shores apper- 

 taining to these two beds must have been very different, if, as we 

 have every reason to suppose, the country was elevated and de- 

 pressed en masse. In the Saxicava Sand, strictly littoral sbells, as 

 Mya arenaria and Mytilus edulis, are found with both valves 

 attached, and apparently in situ, at a height of about 100 feet 

 above the river, and at the base of the mountain. A sea level of 

 this elevation would reach in a long bay up the Ottawa as far as 

 Ottawa City. On the St. Lawrence it would not extend above the • 

 rapids, and south of the river it would reach but a short distance 

 from the bank, except along the vallies of tributary streams. It 

 would open into the Gulf of St. Lawrence by a strait of no great 

 widtb. The sea area so characterized would be but a limited 

 upward extension of the Gulf of St. Lawrence, not communicating 

 directly with the ocean, receiving much fresh water, and subject 

 to no ice drift, except that originating on itsown shoves. In such 

 a basin the Mya arenaria and truncata, Mytilus edulis, Tellina 

 groenlandica, and Saxicava rugosa, would find sufficiently conge- 

 nial haunts, though their size might, as we find in some of the 

 localities, be dwarfed by access of fresh water, or the extreme 

 changes of temperature. In such a basin also, there might be 

 deep channels affording passage to the tides, and containing shells 

 of more oceanic character, and these might be expected to abound 

 most toward the open sea on the north east. Locally there would 

 be gravelly beaches, muddy inlets, sand banks, and deep oosy 

 hollows, in each of which different species might predominate.* 



* All these conditions may be observed in the bottom of the present 

 Gulf of St. Lawrence, and in its quieter depths there are beds of clay 

 closely resembling the Leda clay of this paper, and inhabited by two 

 species of that genus of sbell-fish. 



