Figures and Descriptions of Canadian Organic Remains. 305 



the Geological Survey of Canada there are now twenty-one species 

 of Cystideans, about fifty Crinoids, and ten Star-fishes, or in ail 

 eighty-one species of Echinodermata from this formation instead 

 of thirteen. 



"In the Devonian formation several forms resembling Cystidese 

 have been referred to that group of organisms ; but it remains still 

 to be shewn that they are true Cystideans. The weight of the 

 evidence tends to shew that the race was ushered in with the first 

 living inhabitants of the deep — attained its greatest development 

 in the latter portion of the Lower Silurian era, and died out about 

 the time of the commencement of the Devonian. Of its associates 

 in the Primordial Zone, the Brachiopoda, Pteropoda and Bryozoa 

 remain to the present day. The trilobites held their possession of 

 existence until the Carboniferous period, and the graptolites disap- 

 peared early in the Upper Silurian. With the exception then of 

 the graptolites, the Cystidesewere the first race that became extinct." 



In the remainder of the paper the scientific reader will find 

 much curious investigation of the structures of the Crinoids and 

 Cystideans of the silurian rocks, and the differences between them 

 and their nearest modern relatives. These things are interesting 

 in themselves, and raise curious questions as to the use of these 

 perished creatures, and the conditions of life to which they were 

 adapted. These questions we can answer only in part, but it is 

 only by patient investigation of the minutest structures that we 

 can hope to have even a general idea of the part they played in 

 the works of the Supreme. Certain it is at least that they had 

 an important share in gathering the materials of some of those 

 limestone beds on which our country is based, and that the study of 

 our numerous Canadian species is contributing largely to our know- 

 ledge of their mode of life. The investigations in this volume of 

 the true nature of the orifices of Cystideans are of especial impor- 

 tance in this respect. No less than nineteen species are described 

 in this decade, and many of them are illustrated by admirable 

 figures, which equal, and we rather think far surpass anything 

 hitherto done for American fossils. Another valuable paper by 

 Mr. Billings, relates to the fossil Star-fishes of Canada. 



Mr. Salter's contribution to the volume is a description of a singu- 

 lar new genus allied to Cystideans or Star-fishes if not connect- 

 ing these groups. 



Mr. Jones gives descriptions and figures of nine species of little 

 bivalve Crustacea allied to the Cypoits and Cytheridea that now 



