58 CANADIAN FOSSILS. 



one plate fitting into the corresponding notches of those in contact 

 with it above and below. The edges of the large joints are nodulose, 

 and the column is much larger at the base of the cup than at its 

 lower extremity. One specimen tapers from one-fourth of an inch 

 to one-eighth in a length of fifteen inches. 



The form of the alimentaiy canal appears to vary in difierent parts 

 of the same column, being usually more or less star-shaped, but 

 sometimes circular. The separate large joints are generally seen in 

 the shape of flattened rings, with the outside margin thick and 

 rounded, but thinned down to a sharp edge around the perforation 

 of the centre. 



The columns of this species very much resemble those of Schizo- 

 crinus nodosus (Hall, Palasontology of New York, vol. i., pi. JO), and 

 were always so called in Canada, until a number of specimens were 

 found with the heads attached. The figures and description of that 

 species however given by Professor Hall, show that it had four plates 

 in the primary rays, and must be therefore not only specifically but 

 generically distinct from G. ramulosus. I think that a large propor- 

 tion of those great columns so common in the Trenton limestone on 

 the Ottawa should be referred to this species and to G. yriscus. 

 Specimens four or five feet in length are sometimes seen in the 

 quarries, and some of the crushed heads, including the arms, are 

 seven inches in length. 



A highly interesting specimen in the cabinet of Dr. Van Cortlandt 

 of the city of Ottawa, consists of the inside of a cup two inches 

 and a half in length and one inch and seven-eighths in diameter, 

 at the base of the free arms. It had been completely embedded 

 in the stone, but by some means the body has been extracted, 

 leaving all the plates lining the cavity in their natural position. 

 Each of the plates has a small tubercle in its centre, on the inside. 

 The impression of a fragment of the column one inch and a half in 

 length from the base of the cup downwards still remains. The 

 characters of the column are precisely those of many of the large 

 ones usually seen without the heads attached. If therefore any of 

 these large columns belong to this species, then in their advanced 

 age they must have lost their nodulose character, because they are 

 smooth instead of nodose, as is the case with the smaller specimens 

 in the collection of the Survey which have the heads attached. It 

 appears to me that in all the species of Glyptocrinus the columns 

 were ornamented until past the middle age, and that afterwards they 

 became plain. 



