NEMATAXIS. 



(Page 552). 

 Nemataxis fibkosus, Hall. 



Fig. 16. A specimen imbedded in the rock and fractured so as to 

 show the internal structure, natural size. 



Fig. 16. A part of the same. x6. 



Fig. 17. A portion of a specimen showing the oval cell apertures dis- 

 posed in regular longitudinal rows and maculae destitute of 

 cell apertures. 



Fig. 18. A portion of a specimen having the cell apertures obliterated 

 by a calcareous deposit. 

 Hamilton group. Erie county, N'. Y. 



651 



