CORALS AND BRYOZOA. 205 



LlCHENAHA BULLATA, n. Sp. 

 PLATE LVII, FIGS. 12, 13. 



ZoARiUM consisting of free or incrusting explanate fronds. Cell apertures 

 circular or oval, diameter .50 mm. Peristomes moderately thick, the pos- 

 terior portion the more strongly elevated, a little oblique. Inter-apertural 

 space occupied by vesicles nearly equal in diameter to the cell apertures. 

 Sometimes on portions of a frond the vesicles are much enlarged and the 

 cell apertures correspondingly small. 



Formation and locality. Hamilton group, four miles south of Le Roy, Genesee 

 county, N. Y. 



LiCHENALIA OPERCULATA, n. Sp. 



NOT FIQUBBD. 



ZoARiuM consisting of free or incrusting lamellate expansions, or of masses, 

 formed by the superimposition of successive layers of growth ; thickness of 

 fronds from .50 to 5 mm. Cells tubular, cylindrical, rectangular or slightly 

 oblique to the surface ; septa thin, moderately frequent. The intercellular 

 space is vesiculose ; near the base the vesicles are large and very irregularly 

 disposed ; they are smaller and regularly superimposed above, frequently 

 having the appearance of walled septate tubuli, with from twenty-five to 

 forty septa in the space of 5 mm. Cell apertures circular, often pustuliform, 

 oblique to the surface, diameter .40 mm., radiating from the centers of the 

 monticules, generally forming closely disposed, diagonally intersecting rows, 

 frequently in contact, usually operculated ; the opercula are conspicuous, 

 consisting of thin, slightly convex plates, extending entirely across the cell 

 apertures. Peristomes thick, sometimes equally elevated, but usually the 

 posterior portion is the more prominent, oblique, longitudinally striated. 

 Inter-apertural space occupied by bullae, which are marked by short, broad, 

 interrupted striations ; when the frond becomes slightly worn these bullae 

 are broken away, leaving the appearance of shallow angular pits. Surface 

 marked by broad, rounded monticules, the centers of which are distant from 



