590 



Report of the State Geologist. 



walls of cells in axial region very thin, becoming much thickened 

 and sometimes slightly moniliform in the peripheral region. 



This genus has been placed in this family because the author 

 of the genus says that mesopores occur, but in a large number of 

 sections of the type species that I have examined, the " meso- 

 pores" have much more the appearance of young cells. The 

 genus should probably be placed in the family Amplexoporid^- 



I^icHOLsoNELLA, TJlrich. 

 (Geol. Sur. 111., Vol. YIII, p. 374.) 

 Type, I^icholsonella ponder osa, Ulrich. 



Zoaria consisting of irregular, intertwining flattened branches 

 or fronds. Cells tubular with a few diaphragms in the peripheral 



Fig. 18^. Nicholsonella cumulata. Natural size. 



Fig. 184. Surface of the same, xl2. 



Fig. 185. Transverse section, xl8. 



Fig. 186. Vertical section, xl8. 



region; apertures circular, with a faint granular peristome; 

 intercellular space occupied by numerous angular mesopores or 

 tubuli, that more or less completely isolate the cell tubes; walls 

 of both the cell tubes and mesopores thin ; mesopores with thick 

 and numerous tabulae or diaphragms. 



