242 FREDERICK W. SARDESON 



and which probably belong to that species. Three figures published^ 

 are reproduced here as Figs. -8, 9, 10. 



Associated with discoid Crinoidal roots, in the Ordovician are the 

 similar fossils known as Lichenocrinus . Several species of these 

 have been described with such thoroughness, especially by Meek," 

 and with such citations as to make a review of the genus here seem 

 unnecessary. The crateriform bases of these fossils are known to 

 bear a slender stalk of polygonal plates in some cases. Yet this 

 stalk is not known to have been identified, with certainty, as a Crinoidal 

 structure. Lichenocrinus can be treated only as a problematic 

 structure, notwithstanding concise knowledge of the fossils as they 

 occur, and it may therefore be quite neglected here. In a large number 

 of specimens of it which I have collected, nothing new has appeared. 

 In regard to the discoid Crinoidal roots on the contrary, their struc- 

 ture has not been thoroughly described and they invite further study 

 n this respect, as well as identification with recognized species of 

 Crinoidea. 



NEW DESCRIPTIONS 



In order to faciHtate scientific description a generic name is used 

 here to include several taxonomic species of Crinoidal roots. This 

 generic name, as in case of Lichenocrinus and of Camarocrinus, is 

 not expected to coincide with any one generic term based upon de- 

 scribed crowns and will be superseded by such generic terms as often 

 as root structures are identified specifically with previously described 

 crowns. 



PODOLITHUS n. gen. 



Primitive discoid or conical Crinoidal root-structures with more or 

 less lobate margins and with a fixing-plate. Region about the stem- 

 scar not depressed. Type Podolithus schizocrinus, n. sp., Fig. 11. 

 Podolithus strophocrinus nom. nov. 



(Figs. 8, 9, 10) 



To this type belong stem-bases which are low, conical, i to 5*^™ in 

 diameter, with nearly entire margin and generally circular outhne, 

 although by accident sometimes quite irregular. Fig. 8 shows the 

 most unsymmetrical specimen found, while Fig. 10 represents one 



I Op. cU., PI. XII, Figs. 14, 15, 16. 2 op. cit., pp. 44-52. 



