196 PALEONTOLOGY OF NEW YORK. 



by its somewhat more numerous and prominent monticules, the more pronounced 

 depression at the center, the closer disposition of the cell apertures, the 

 absence of inter-apertural pits or vesicles, and the very few oporcula : from 

 F. variapora, to which it bears a close general resemblance, by the depression 

 at the center of the monticules, the oblique cell apertures, and absence of 

 mesopores : from F. umbilicata by the less pronounced depression at the center 

 of the monticules, the oblique cell apertures and absence of mesopores : from 

 F. serrnlata and F. confertipora by the depression in the monticules, the oblique 

 cell apertures and absence of mesopores. 



Formation and locality. Hamilton group, West Bloomfield, N. Y. 



LiCHENALIA SCBTRIGONA, n. Sp. 



NOT. FiaORBD. 



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

 by the accretion of successive layers of growth ; under surface a thin epitheca 

 with strong concentric wrinkles or undulations, frequently irregular or con- 

 torted, and also with fine radiating markings, caused by the recumbent 

 portions of the cells ; thickness of fronds from 1 to 5 mm. Cells tubular, 

 rectangular to the surface, walls thin ; septa moderately frequent. Inter- 

 cellular tissue vesiculose, vesicles large, frequently having a diameter of 

 between .30 and .40 mm., and rarely of more than .50 mm. ; near the base 

 they are always very irregularly disposed, and usually so for the whole depth 

 of the frond, but sometimes more regularly superimposed above, but never 

 having the appearance of walled, septate tubuli. Cell apertures ovate or sub- 

 trilobate, length .33 mm., width three-fourths the length, irregularily dis- 

 posed, sometimes in contact, at other times separated by more than the 

 width of an aperture. Peristomes moderately thick, usually equally 

 elevated, but sometimes the posterior portion is the stronger, and also shows 

 faint indications of denticulations. The surface is marked by maculae, 

 destitute of cell apertures, the centers of which are distant about 8 mm.; 

 the adjacent apertures are larger than the others, more nearly circular, and 

 have an indistinct radiation therefrom. 



