222 Geological Survey of Canada. 



A very interesting point, which is the burthen of this decade, 

 is the fact thai in the limestone of Pauquette's Rapids, as else- 

 where in Lower Canada, the fossils which in New York are divid- 

 ed among the Chazy, Trenton, Black River, and Birdseye lime- 

 stones, co-exist in a single bed, indicating no doubt a greater 

 uniformity in the condition of the sea bottom. 



Mr. Salter's decade closes with a notice of a singular genus, 

 which has hitherto puzzled paleontologists, the Receptaculites, 

 long since figured by Hall in the fossils of New York, but of 

 which new species have been found in Canada and Australia, 

 Mr. Salter regards it, notwithstanding its comparatively gigan- 

 tic size, as belonging to Foraminifera and al ied to the genus 

 Orbitolites. The conjecture is clever and not improbable; and, 

 if true, it will not only give the Foraminifera a great antiquity, 

 but show that, like some other families, they began to exist in 

 gigantic forms unequalled by their degenerate successors. 



Decade 4th is the work of Mr. Billings, and describes all " the 

 crinoids of the silurian rocks of Canada, of which specimens have 

 been procured, in such a state of preservation, as to admit of their 

 being characterized" ; — about fifty species in all. Mr. Billings 

 very properly prefixes to his description of the species, an intro- 

 ductory account of their organization, so plain and clear, that no 

 one can find much difficulty in studying these curious fossils after 

 reading it. The crinoids are stalked starfishes, of so curious and 

 complex organization, that they attracted the popular fancy long 

 before there was any science of geology. They furnished the old 

 Britons with natural necklaces, and they have been known as " fairy 

 stones," " St. Cuthbert's beads," " screw stones," " pulley stones," 

 and lastly, as " stone lilies." When perfect, the typical crinoid 

 presents a long flexible column or stalk made up of a series of flat- 

 tened beads, cuiiously worked into articulating surfaces where 

 they touch each other, and penetrated by a central perforation, 

 through which extends a continuation of the body of the creature. 

 On top of the stalk was a cup, made up of a number of ornamen- 

 ted plates, joined at the edges, and containing the viscera of the 

 animal. From the edges of the cup sprouted forth jointed arms 

 extending around and serving as organs of prehension ; and in a 

 cover of smaller plates, probably often flexible, was the mouth, 

 extended sometimes into a tubular proboscis. 



The particular description of their parts, given by Mr. Billings, 

 is worthy of being extracted here, for the benefit of students and 

 collectors. 



