212 PALEONTOLOGY OF NEW YORK. 



monticules extend to the center and are not larger than those on other por- 

 tions of the frond. 



The cell apertures and mesopores of this species are very similar to F. 

 ponderosa of the Lower Helderberg group, but it may be distinguished by the 

 numerous monticules and the regular disposition of the vesicles, forming septate 

 tubuli ; the surface of that species is without monticules or maculae, the vesicles 

 are irregularly disposed, and the spines on the peristomes are stronger : from 

 F. variapora it is distinguished by the more numerous monticules, the smaller 

 and more nearly circular cell apertures, their closer disposition, their uniform 

 size and the absence of a non-celluliferous space at the center of the monticules: 

 from F. serrulata, by the more numerous monticules, the much closer disposition 

 of the cell apertures and the minute mesopores : from F. scrobiculata by the 

 prominent monticules, the closer disposition of the cell apertures and the 

 minute mesopores. 



Formation and locality. Hamilton group, Moscow, Livingston county, N. Y. 



FiSTULIPOBA SCROBICULATA. 



I'LATK LVm, FIGS. 17, 18. 



ThaUostigma scrobiculata. Hall. Trans. Albany Institute, vol. x, p. 184. 1881. 



Report of State Geologist for 1883, p. 20. 1884. 



ZoARiUM consisting of explanate, free or incrusting fronds, or of masses formed 

 by the superimposition of successive layers of growth ; the fronds observed 

 vary from .50 to 2 mm. in thickness; the under surface consists of an 

 epitheca, strongly wrinkled concentrically, and showing radiating markings, 

 caused by the recumbent portion of the cell tubes. Cells tubular, for a short 

 distance nearly parallel with the epitheca, but for nearly their entire length 

 rectangular, or slightly oblique to the surface, invariably opening directly 

 outward, walls thin, smooth ; septa infrequent. Intercellular space vesicu- 

 lose ; near the base the vesicles are irregularly disposed, more regul.arly 

 above, having the appearance of septa dividing the space between the cell 

 apertures, and occurring at irregular intervals, sometimes four or five in the 

 space of 1 mm , at other times only one or two. Cell apertures circular, 



