458 THE CANADIAN NATURALIST. [Dec. 



with the Llandeilo measures, with the representatives of the stiper 

 stones coming in between. The fossils occur in the lower member 

 of the lingula flags. Thirty-three species are now known from 

 these measures, and, with the exception of two species, have all 

 been discovered by Mr. Hicks. From this cause he proposed to 

 term this group of rocks the Minevian division, a name derived from 

 the ancient designation of St. David's. The largest form of trilo- 

 bite yet found in Great Britain (sometimes twenty inches in 

 length, and called Paradoxides) is characteristic of these beds, and 

 the smallest known trilobite (Agnostus) is also peculiar to this for- 

 mation. With the Crustacea occur several forms of mollusca of a 

 low order, A few species of Cystidea are found, also several 

 species of sponges. The fauna of St. David's is represented in the 

 neighborhood of Dolgelly. The series is doubtless the equivalent 

 of well known beds in North America, Bohemia, Sweden, and 

 Spain. The result of the recent exploration has been to carry 

 down the lower forms of life only. As we descend, the higher 

 forms of life successively disappear. When we reach the lower 

 beds, only annelids remain. 



The President said every geologist must feel infinitely indebt- 

 ed to Mr. Hicks for his discovery, and to Mr. Salter for his lucid 

 explanations. With respect to the general position of these beds, 

 it appeared to him that they formed the natural base of that great 

 system of rocks, the Lower Silurian. In Sweden, in America, in 

 Germany, and all over the world, this primordial zone was the 

 natural base of the Silurian or great Lower Trilobitic system. 



Principal Dawson said it was very pleasant to find so close 

 a parallelism between the Lower Silurian rocks of this country and 

 of Canada and other parts of North America. As Mr. Salter had 

 mentioned, the great Paradoxides was found in Newfoundland in 

 rocks of probably the same age as the Lingula flags. The same 

 rocks ran alono: Nova Scotia, beins; the cold-bearins: rocks of that 

 country, but the Paradoxides had not yet been found in them. 

 There -was a continuation of the same great zone in Massachusetts ; 

 and in Canada, there were the very remarkable rocks constitu- 

 ting the Quebec group, containing similar fossils, and being, 

 as Sir William Logan believed, a deep-sea formation of Lower 

 Silurian age ; so that all this brought what was known in 

 America into harmony with what was found in this country. 

 The occurrence of sponges in these rocks had been mentioned by 

 Mr. Salter. The same thing had been ascertained in Canada by 

 Mr. Billings in rocks probably nearly as old. 



