Ivi PEOCEEDIK^GS OF THE GEOLOGICAL SOCIETY. 



stances, and some inquirers may dispute this nomenclature with 

 respect to the Lower Silurian lavas and ashes ; but practically it was 

 found by the author of the book, and by his colleagues Professor 

 Jukes, Mr. Selw^^n, and Mr. Aveline, that until this conclusion was 

 arrived at the igneous rocks could not be reduced to any systematic 

 order, whilst as soon as it was come to the whole seemed to be intelli- 

 gible, and, instead of presenting further difficulties, the interstratified 

 igneous masses rather aided in the mapping and helped to explain 

 the relations of all the parts to each other. 



The second partof the volume consistsof adescription by Mr. Salter of 

 the fossils illustrative of the memoir, accompanied by numerous plates. 



On the progress of that ably conducted survey in Canada which 

 has produced such good results. Sir William Logan informs me that 

 the late investigations have been devoted, in the first place, to working 

 out in more detail the structure of that region on the south side of the 

 St. Lawrence in Eastern Canada which is occupied by the Quebec 

 group. That group, instead of including the " calciferous " and 

 " chazy," is now placed between them ; and it has been found con- 

 venient to separate it into a lower, a middle, and an upper division, 

 the lower comprehending nearly all the fossils by which the horizon 

 of the group is determined, and the middle containing aU. the mag- 

 nesian rocks and metalliferous deposits which give the Lower Silurian 

 formations an economic value. 



The geologists have also further followed out, on the westward of 

 what was previously known, the distribution of the three great bands 

 of limestone belonging to the Laurentian system, the upper band 

 being that which holds Eozoon. 



It had been already notified to us through Dr. Dawson that frag- 

 ments of Eozoon had been found preserved in carbonate of lime. Both 

 the large and small canals were in this case filled with calcspar. 

 The specimens come from a micaceo-calcareous schist from the Lau- 

 rentian of Madoc, where the rocks are not so much altered as they 

 are in GrenviUe. This year one of the assistants, Mr. Yennor, in 

 tracing this bed into Tudor, the next township to that of Madoc 

 (which is north of Belleville, west of Kingston, Lake Ontario), has 

 been so fortunate as to find a fossil whose white calcareous skeleton is 

 preserved in a dark-coloured arenaceo-micaceous limestone, with 

 minute grains of carbonaceous matter. The limit of the form is 

 well preserved on one side ; and although the minute structure is 

 obscure, Dr. Dawson pronounces the fossil to be Eozoon Canadense. 

 We may expect ere long to receive a further communication on this 

 important subject from Sir WiUiam Logan himself. 



The study of the numerous questions which arise from a careful 

 examination of rocks has been much facilitated by the recent pub- 

 lication of several works treating specially of this branch of geology. 

 Professor von Cotta's well-known treatise has been translated by 

 Mr. Lawrence, one of our Fellows *, with the advantage of correc- 

 tions and additions by the author, which make it, in fact, the third 

 «• Eocks classified and described, by B. von Cotta : an Enghsh edition, by 

 Philip Henry Lawrence, F.G-.S. Longmans, 1866. 



