106 



Canadian Record of Science. 



greater part of the fragments in the agglomerate, by the 

 irregularity of deposition and want of regular bedding, by the 

 fact that nearly all the material of the agglomerate belongs 

 to rocks known to include the locality, and by the character 

 of the paste, which may be regarded as volcanic ash and 

 debris cemented by dolomite. It is also to be observed that 

 Helderberg fossils occur not only in the limestone, but also 

 occasionally in the paste of the agglomerate itself. 



In 1880 Mr. Donald, now Prof. Donald, who had collected 

 at St. Helen's Island, and had access to the collection in 

 McGill College, determined and published a list of these 

 fossils, comprising sixteen genera and thirty-six species. 1 



Since that date annual Geological excursions have added 

 a few more species, and better specimens of others person- 

 ally known, to the McGill collection ; and the object of the 

 present paper is to summarize all the work that has been 

 done in connection with this isolated patch of Silurian rock. 



The following is a list of the fossils so far determined, 

 also for comparison, those which are common to the New 

 York, Gaspe" and Nova Scotia fauna. These are denoted by 

 asterisks : — 



Lower Heldebbbeg Limestone of 

 St. Helen's Island. 



Crinoid stems 



Stenopora 



Chaetetes abruptus 



Callopora incrassuta. . 

 Favotites Helderbergix. 



Favosites Sp. t • . • 



Zaphrentis corticata . . . 

 Zaphrentis Roemeri. . . . 



Zaphrentis Sp. ? 



Heliolites 



New 

 York. 



Gasp6 



and 



Bay des 



Chal'urs 



Nova 

 Scotia. 



1 Canadian Naturalist. Vol. IX., p. 302. 



