DISCOID CRINOIDAL ROOTS AND CAMAROCRINUS 253 



The pockets or camarae of Camarocrinus are not internal divi- 

 sions but invaginations of the outer wall, hence communicating not 

 vi^ith the interior but the exterior. The internal partitions of Podo- 

 lithus and of Lichenocrinus, too, correspond not v^ith its "camarae" 

 but with the canals of the interior, Fig. 27, and with partitions of the 

 medio-basal chamber 0, Fig. 31, and of other interspaces of the 

 closely folded "double" wall. Camarocrinus is not to be considered 

 as "double walled" but single walled. The wall, folded upon itseK 

 is united "by many short, stout, blunt processes,"^ and these processes 

 may be considered as homologous with the internal partitions of 

 Podolithus and of Lichenocrinus. The inner surface of the wall of 

 Camarocrinus is in fact marked by knobhke extensions, especially 

 of the larger of the plates, and by pore-like enlargements of the sutures. 

 Maceration and weathering must tend to open these latter, one after 

 another, to the exterior. I am in doubt, therefore, whether the pores 

 through the walls which Schuchert so clearly represents,'' were origi- 

 nally open to the exterior or not. Presuming that they were, their 

 nature may be the same as the pores on the colunm, though not seen 

 on the base of Podolithus anomalocrinus. I have not discovered in 

 the specimens of Camarocrinus the particular plate which is the 

 original fixing-plate, but it might be seen on favorably young speci- 

 mens. 



Excepting possibly the supposed pores, the structures of Camaro- 

 crinus are those of Podolithus. Further, the observation may be 

 made, that since Schizocrinus Hall and Scyphocrinus Zenker belong 

 to the same family, Glyptocrinidae according to Bather, the probability 

 that Podolithus schizocrinus belongs to the one, gives greater weight 

 to the contention that Camarocrinus in part, at least, belongs to the 

 other. 



EXPLANATION OF FIGURES 



Fig. I. — Base of a Crinoidal column, on a coral, from the Trenton limestone; 

 after Hall. 



Figs. 2, 3. — Crinoidal roots from the Niagara limestone; after Hall. 



Figs. 4, 5. — Root with fragment of column, from shales of the Cincinnati stage, 

 and part of column of same, magnified; after Meek. 



Figs. 6, 7. — Roots or "dorso-central plates," from shales of the Cincinnati 

 stage; after Wachsmuth and Springer. 



I Schuchert op. cit., p. 263. 2 Op. cit., PI. XL, Figs. 8 10. 



