Of the Vicinity of Montreal. 407 



a variety of other species, inhabitants, at least in part, of deeper 

 water; but I could not certainly ascertain the superposition of 

 these beds. I presume that it is, in descending order ; littoral 

 sand, sandy clay deposited in deeper water, a thin layer of deep 

 sea clay, and boulder clay. 



At this place, in addition to all the species already noticed, I 

 have found : 



Buccinum ciliatum. 



Buccinum undatum. 



Adraete viridula. v 



Acmsea caeca. 



Nucula minuta. 



Lacuna neritoides. 



Natica helicoides ? 



Fusus scalariformis. 



Serpula vermicularis 



Margarita arctica. 



Modiolaria discors. 



Rissoa minuta. 



Trjchotropis arctica. 



Cytheridea Mulleri ? 

 All these mollusks and articulates are known as inhabitants of 

 modern seas, and most of them are boreal or arctic species. 



In addition to these, there are at this place several species of Fo- 

 raminifera, very abundantly distributed in the clay, and masses of 

 silicious spicula of a sponge (Tethea). These sponges have evi- 

 dently abounded in this quiet depression, and being covered by 

 clay, their spicula have, on the decay of the animal matter, been 

 imbedded in situ, so that at first sight they look little masses of 

 asbestus, for which, indeed, they have been mistaken. 



The large number of additional species collected at this place, 

 shows that much may be dene in adding to the fauna of this 

 period. The circumstance which has favoured the accumulation 

 here of so many species, is apparently the sheltered situation of 

 this little hollow, and the deeper water in its bottom, as compared 

 with that on the neighbouring ridges; on which, however, many 

 ef the shells may have lived, and may have been drifted into the 

 intervening trough, so that we have here the inhabitants of dif- 

 ferent depths, or perhaps, more properly, a very rich spot of the 

 sea bottom representing the laminarian zone intermediate between 

 the purely littoral and coralline belts, but in its upper bed tend- 



