280 PALjEONTOLOGY OF NEW YORK'. 



sisting of a main tube or axis from which proceed laterally, at more or less 

 regular intervals, simple tubular cells, and at irregular distances other tubu- 

 lar extensions which have the same manner of growth as the primary 

 axis. This mode of growth is indefinitely continued, so that comparatively 

 large surfaces are covered by the fronds. The coll tubes are sub-cylindrical, 

 transverse section broadly oval, length from 2 to 2.50 mm., diameter .50 mm., 

 turning abruptly outward at the extremity, the apertures opening on a line 

 parallel with the axis of the branch and very broadly oval or nearly circular. 

 Cells generally alternating, distant on the same side of the main axis from 

 1 to 1.25 mm. ; the angle of divergence from the axial tube is usually from 

 thirty-five to forty degrees. Surface marked by numerous, very fine, sharp, 

 transverse striations, and nearly equally fine longitudinal striae, often pre- 

 senting a minutely cancellated appearance ; on many of the cell tubes there 

 are also more prominent annulations and wrinkles. 



On account of the frequent occurrence of the cell tubes, their margins are 

 in contact for their entire length, the frond presenting a much more compact 

 appearance than usual in species of this genus and frequently so closely resem- 

 bling the genus Reptaria, that it is sometimes difficult to distinguish its generic 

 relations. 



Formation and locality. Hamilton group, Darien Centre, Genesee county, 

 N. Y. 



Hederella magna. 

 plate lxv. fig. 15. 



Hederella magna. Hall. Trans. Albany Institute, vol. x, p. 195. 1881. 

 Report of State Geolopst for 1883, p. 55. 1884. 



ZoARiUM parasitic, usually occuring on Cyathophylloid corals, most frequently 

 on Heliophyllum Haiti ; procumbent, .attached for its entire length, consisting 

 of an axial tube from which proceed lateral, simple, tubular cells, and at 

 infrequent intervals tubular extensions having the same manner of growth 

 as the primary axis ; length of cell tubes from 2 to 3 mm , diameter a little 

 more than 1 mm., transverse section broadly oval ; at first rapidly expand- 



