Canadian Goleoptera. 255 



5. P. litstrans, Lee. Ann. Lye, v. V, p. 181, Cal. ■ 12 mm. 

 •468 in. 



Explanation of Plate II. 



Fig. 1. Elaphrus pallipes, Horn, var. purpurans. n. var. ? 



" 2. Pteroetichus stenopus, n. sp. cf 

 " 3. " pulvinatus, n. sp. " 



" 4. <' mutus, Say " 



On Some Causes Which May Have Influenced 

 the Spread of the Cambrian Faunas. 



By G. F. Matthew, M.A., F.R.S.C. 



The attention given of late years to the succession and 

 the regional variation of the Cambrian faunas, and the dis- 

 covery of these faunas in different parts of the earth where 

 they were previously unknown, has enabled us to form a 

 judgment, imperfect though it may be, of the causes which 

 have effected the development of these faunas. 1 



Prof. Jules Marcou has given much attention to this sub- 

 ject, and has stated his opinions in a series of articles pub- 

 lished in the American Geologist. 2 In these articles he at- 

 tributes the peculiarities of the Cambrian faunas in various 

 regions of what is now Europe and North America to the 

 peculiar distribution of the land and sea in those early 

 times. He supposes a land connection between the north 

 of Europe and North America as giving the means of 

 transit, along shore lines, for the resembling faunas of 

 Scandinavia and Acadia, and conceives of a land-barrier 

 along the line of the Appalachian ranges as an obstacle to 

 the migration of the Olenellus fauna eastward. A land- 

 barrier such as Barrande has described in his great work 

 on the Silurian system in Bohemia, is supposed by Marcou 



'The remarks which I make in the following pages are rather 

 suggestions than positive opinions, as to the causes which have 

 produced changes in the Cambrian faunas, or have led to their 

 annihilation. 



2 The lower and middle Taconic of Europe and North America. 



