CORALS AND BRYOZOA. 85 



and very strongly elevated, projecting over and partially concealing the aper- 

 tures. Monticules distinctly elevated, the centers distant from each other 

 about 3 mm., bases in contact. Near the center of the monticules the cell 

 apertures present a somewhat confused appearance. Intercellular space 

 occupied by septate tubuli. 



This species can be easily distinguished by the crowded appearance of the 

 cell apertures, and their very prominent, denticulated posterior margins. 

 Formation and locality. Upper Helderberg group, Falls of the Ohio river. 



Odontotrypa, s. g., Hall. 1886. 

 LicHENALiA (Odontotrypa) alveata. 



PLATE XXX, FIGS. 24-27. 



LicJienalia alveata. Hall. Trans. Albany Institute, vol. x, abstract, p. 10. 1881. 



" (Odtmtotrypa) alveata. Report of State Geologist for 1885, advance sheets. Expl. pi. 30, figs. 



24-27. 18S6. 



ZoARiUM consisting of very thin expansions. Cells oblique, frequently imbricat- 

 ing. Apertures oblique to the surface, trilobate, diameter .40 mm. ; irregu- 

 larly and very clo.sely arranged, generally in contact. Peristomes thin, 

 anterior portion slightly elevated ; posterior portion more strongly elevated, 

 and having two prominent denticulations, producing a cresentic projection. 

 Surfiice with maculae destitute of cell apertures, depressed, elongate, length 

 4 mm., width 1 mm. Intercellular space vesiculose. 



This species may be distinguished by its large, closely arranged, imbricating 

 cells, and elongate, depressed maculae. 



Formation and locality. Upper Helderberg group. Falls of the Ohio river. 



Glossotrypa, s. g., Hall. 1887. 

 LicHENALiA ? (Glossotrypa) paliformis. 



PLATE XXXI, FIGS. 15-18. 



Lichenalia paliformis, H.vll. Trans. Albany Institute, vol. x, abstract, p. 11. 1881. 



(Glossotrypa) paJi/onaU. Report of State Geologist for 1885. Expl. pi. 31, figs. 15-18. 1887. 



ZoARiuM tubular, cylindrical; diameter of frond 2 mm.; thickness of zoarium .40 

 mm. Cells tubular,with frequent narrow projections (semi-diaphragras) from the 



