214 PALEONTOLOGY OF NEW YORK. 



which are distant from each other from 5 to 6 mm., very much depressed 

 and destitute of cell apertures ; the apertures immediately adjacent to the 

 depressed portion are larger and much more oblique than on other parts of 

 the frond. 



The surface varies in appearance according to the degree of preservation ; 

 when weathered the peristomes are stronger and more elevated, and the 

 mesopores more conspicuous than when the frond is perfectly preserved ; in 

 the latter case the intermediate pits are very obscure. 



This species may be distinguished from F. variapora by the circular, slightly 

 smaller and more distant cell apertures, the depressed centers of the monticules, 

 the larger mesopores, and the more irregular vesicular structure ; in the 

 latter species they have the appearance of septate tubuli : from Lichenalia 

 stellata by the deeper depression at the centers of the monticules, the smaller 

 and more distant cell apertures, the equally elevated peristomes, the presence 

 of mesopores, and the more irregular arrangement of the vesicles : from F. ser- 

 rulata by the depression in the monticules, the larger and more oblique cells 

 near their centers, the closer disposition of the apertures, and the absence of 

 serrulations on the peristomes. 



Formalion and locality. Hamilton group, York, Livingston county, N. Y. 



FiSTULIPOBA SERRULATA. 



PLATE LVm, riGS. 6-8. 



Thallostifftna serrulata. Hall. Trans. Albany Institute, vol. x, p. 185. 1881. 

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



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

 composed of successive layers of growth. Cells tubular, cylindrical, sep- 

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

 directly outward; septa very infrequent or obsolete; cell walls com- 

 paratively thick, longitudinally striated Intercellular tissue composed of 

 vesicles, which are sometimes very irregularly, at other times regularly 

 disposed, but not having the appearance of tubuli divided by septa as 

 in many species, but of vesicles superimposed in somewhat regular order. 



