36 Post-Pliocene Deposits of the St. Lawrence. 



hyalina ; and there is also a Tubulipora closely resembling that 

 found at Beauport. The shell of a dead Balanus contained a 

 little fine sand, among which were small and much rubbed speci- 

 mens of a Polystomella or Nonionina, and fragments of spines of 

 Echini. This stone is indeed almost a precise modern counterpart 

 of those buried in the drift at Beauport ; and they, like it, probably 

 lay in the bottom of a sea loaded in spring with boulder-bearing 

 ice. 



I had almost omitted to mention that some of the stones from 

 Beauport, with Balanus, Bryozoa, &c, bear on their surfaces 

 distinct marks of glacial action, in their polish and striation ; and 

 that just as in exposed situations in modern seas, their animal 

 tenants have evidently selected the re-entering angles and least 

 exposed surfaces for their habitations. 



II. Fresh-water Shells in the Post-pliocene Deposits. 



I have on several occasions found specimens of Limnea in the 

 Post-pliocene clays, but always suspected some accidental inter- 

 mixture. I have been favoured in the past summer, by Andrew 

 Dickson, Esq., with specimens of land and fresh-water shells from 

 the bank of a brook emptying into the Mississippi, a tributary of 

 the Ottawa, two miles below Pakenham Mills, and at an elevation 

 of about 266 feet above Lake St. Peter. They were found in 

 sand and gravel containing TeUina Grcenlandica, and which Mr. 

 Dickson thinks is an undisturbed tertiary deposit. The specimens 

 furnished to me afford many internal evidences which would lead 

 me to the same conclusion. The species present are : — 



Valvata tricarinata, Planorbis parvus, 



Planorbis bicarinata, Amnicola porata, 



Planorbis trivolvis, Helix striaiella ? 



Lymnea elodes ? 



As may be seen by reference to the paper by Mr. Billings in 

 the first volume of this journal, all these shells now exist in the 

 Ottawa valley. Proof of their existence there in the Post pliocene 

 era would be of great interest ; and though I am fully aware of 

 the many chances that may cause recent fresh-water shells to be 

 mixed with older deposits, I am strongly inclined to believe that 

 these deposits at Pakenham afford such evidence. Their occur- 

 rence is at least deserving of notice, that the attention of geologists 

 may be attracted to the locality. 



