GEOLOGY- AND MINERALOGY. 157 



SCIENTIFIC AND LITERARY NOTES. 



GEOLOGY AND MINERALOGY. 



POST-TERTIARIES, ETC., OF MONTREAL. 



Professor Dawson, Principal of McGill College, has favored us with a copy of a 

 very interesting paper on the Newer and Post Pliocene beds of Montreal and its 

 vicinity, lately read by him before the Natural History Society of that city. The 

 deposits in question, commencing with the lowest, are characterised as follows : — 

 1. The ordinary Boulder Clay ; 2. Leda Clay, an unctuous calcareous clay con- 

 taining a few marine fossils, and reaching in places a thickness of twenty feet ; and, 

 8. Saxicava Sand, a fine-grained sand, in places underlaid or replaced by stratified 

 gravel, and containing marine fossils in the lower part. Boulders occur in the 

 two upper deposits as well as in the Boulder Clay, properly so called. In places, 

 the Leda Clay has been apparently carried off by denudation, the sands and 

 gravel resting directly on the Boulder Clay, or on the underlying Limestone, 

 as at the Mile End quarries, <fec. In a deposit of sand and sandy clay occu- 

 pying a depression between these quarries and a ridge formed by a thick trap- 

 dyke near the house of James Logan, Esq., Professor Dawson discovered (with 

 many already recognised forms) no fewer than eleven distinct species of gastero- 

 pods and lamellibranchiate molluscs, besides a serpula, a cytheridea, several fora- 

 Bcdnifera and the spicula of a sponge — not hitherto described amongst our post- 

 tertiary fossils. In addition to these, several new species, obtained principally by 

 the Geological Survey, the author, and the Rev. Mr. Kemp, from the neighborhood 

 of Montreal, Beauport, and elsewhere, are described for the first time by Professor 

 Dawson in his paper ; thus bringing up the list of new forms due to his determi- 

 nations, to about thirty. As the author observes, these marine shell-bearing' 

 deposits although occurring in various parts of Lower Canada, have not been met 

 with further west than Kingston. During the last two summers we have searched 

 very diligently for their presence amongst our drift and post-tertiary formations, 

 but without success. Our limited space prevents us from entering into a fuller 

 analysis of Professor Dawson's valuable communication, but the geological reader 

 will find the entire paper in the last number of the Canadian Naturalist. 



Professor Owen, in a letter addressed to the editors of the " Annals of Natural 

 History," and published in the November number of last year, has expressed his 

 conviction that the Placodus of Agassiz — a supposed fossil fish of the Triassie 

 epoch — belongs really to the class of Reptiles. This view has been adopted from 

 an examination of specimens of P. Andreani, sent by the well-known mineral 

 dealer, M. Krantz of Bonn, to the British Museum. [The species of Placodus 

 hitherto enumerated, comprise ; P. Andreani, Munster ; P. rostratus, Munster ; P. 

 gigas, Agassiz ; P. Munster, Ag. ; and P. impressus, Ag. The last is from the 

 new red sandstone of Deux Ponts; the other four, from the Muschelkalk of Bam- 

 berg in Bavaria. Teeth, and portions of the cranium are only known.] 'Professor 

 Owen promises further details. 



