250 FREDERICK W. SARDESON 



penetration of foreign substances into the root are probably always 

 walled off from the internal cavity. 



The described new species of Podolithus with species of Lichen- 

 ocrinusmchide all the Crinoidal roots which are known to me to occur 

 in the Galena- Trenton stage. Together they form a series which may 

 illustrate the early evolution of Crinoidal roots from a primitive 

 conical expansion of distributed polygonal plates, over a large circular 

 fixing-plate, to a lobate form with plates in single rows over a deeply 

 cut fixing-plate. Further reduction of the fixing-plate could produce 

 the commonly known cirri with circular, perforated segments. 

 COMPARISON WITH CamarocHnus 



At first sight, the discoid roots appear to differ greatly from Cama- 

 rocHnus, but upon close comparison they are much more ahke, the 

 latter being a modified form of the former. Before trying to show 

 this, the problem concerning CamarocHnus alone requires attention. 

 That problem appears in the recently published work On Siluric and 

 Devonic Cystidea and Camarocrinus, by Charles Schuchert.^ In this 

 work Camarocrinus is discussed in regard to history of the genus, 

 mode of occurrence of fossil specimens, their structures and possible 

 relationships. The discussion appears to be quite exhaustive and 

 the description of the fossils, very thorough. The work is based upon 

 a wealth of best materials of all three known species,^ two of which 

 Schuchert redescribes and one of which he presents as new. I may 

 say further that nothing new or not described by Schuchert was 

 found by me in materials which were obtained through the kindness 

 of Mr. Schuchert and of Mr. Bassler of the U. S. National Museum. 

 Following his thorough discussion Schuchert says in the summary -.^ 

 "The writer reahzes that the last word has not been said in regard to 

 Camarocrinus, and the present work is offered with the hope that 

 some paleontologists will attack the problem from another point of 

 view." 



Schuchert's statement just quoted follows paragraphs in which 

 the belief is expressed, following the opinion of James Hall and other 



1 "Smithsonian Miscellaneous Collections," Vol. XLVII, Part 2, 1904. 



2 A fourth species, C. asiaticus Reed, has been later described. See Paleonto- 

 logia Indica, New Series Vol. II, Memoir No. 3, 1906, p. 88. 



3 Op. cit., p. 269. 



