486 FRANK SPRINGER 



that in specimens preserved as these are it is extremely difficult to 

 determine such structures with certainty. Many foreign bodies may 

 become lodged between the rays which might, in the chemically 

 changed condition of the fossils, be mistaken for small, irregular 

 plates. One may even mistake for interbrachials what may be only 

 fragments of arms, as has actually occurred in one case I know. In 

 my specimen with the substance of the Crinoid preserved the radial 

 and brachial plates are well defined, and there is certainly no sign of 

 any plates meeting their margins between the rays. Assuming them 

 to exist, however, as figured by the learned authors, they may be 

 taken to form part of a flexible integument, and the structure would be 

 in a condition analogous to that of the Carboniferous genus Niptero- 

 crinus, although otherwise there is no resemblance between them. 



Nothing is known of the base ; whether it is dicyclic or monocyclic 

 cannot be ascertained from the specimens. The habitus of this form 

 seems to me rather like that of the Inadunata, from which it is sepa- 

 rated only by the supposed interbrachial structures. It is certainly a 

 strange and interesting genus, as to which we may well wish for more 

 information. If it had been found in the Jurassic, instead of the 

 Ordovician, I think no one would have hesitated to place it among 

 the Pentacrinidae. 



Dr. Bather bases his conclusion as to the ancestral character of 

 this form upon the statement that it is "older than any flexible genus 

 hitherto known, and the interest is enhanced when we see how its 

 structure accords with its age in the eyes of the evolutionist;" and 

 that "Flexibilia have not hitherto been known earlier than the Wen- 

 lock age." In making this statement he must have overlooked the 

 specimens of Taxocrinus described by Billings under Lecanocrinus 

 elegans and L. laevis,^ which are much older than the Wenlock, and 

 at least as old as the stage of Caleidocrinus. They occur in the 

 Trenton Limestone of the Lower Silurian, or Ordovician, at a horizon 

 which has been considered by geologists as substantially equivalent 

 to the Bala of England, which Bather takes to be about equal to the 

 Stage d 4 of Bohemia. And it is, of course, much older than the 

 Wenlock, which is the age of the Upper Silurian, approximately 

 equivalent to the Niagara of America. 



I Canadian Organic Remains, December, IV, Plate IV, Figs. 3, 4. 



