CORALS AND BRYOZOA. 
79 
sometimes entirely covered by an organic deposit, and presenting a pustuli- 
form aspect. 
This species can be easily distinguished by the numerous, conspicuous, sub- 
stellate maculae. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Lichenalia bistriata. 
PLATE XXXII, FIGS. 6-14. 
Lichenalia bistriata, Hall. Trans. Albany Institute, vol. x, abstract, p. 8. 1881. 
“ “ “ Report of State Geologist for 1885. Expl. pi. 23, figs. 6-14. 1887. 
Zoarium lamellate, free or encrusting. Cell tubes without septa. Apertures 
lunate or semi-circular, diameter .40 mm. Anterior portion of the peristomes 
very slightly elevated ; posterior portion strongly elevated, projecting over and 
partially concealing the opening, which is margined by two slight denticula- 
tions. When the surface is worn or macerated the elevated margins become 
obsolete, the apertures appearing simply as lunate or semi-circular openings. 
Surface with slightly elevated maculae, the centers of which are without cell 
apertures, the apertures adjacent to these radiate from them and are more 
oblique than the others. Intercellular space septate. 
This species resembles L. lunata , but may be distinguished by the strongly 
elevated cell margins, and the absence of septa in the cell tubes. 
Formation and locality. Upper Helderberg group, Falls of the Ohio river. 
Lichenalia geometrica. 
PLATE XXXII, FIGS. 21-23. 
Lichenalia geometrica, Hall. Report of State Geologist for 1885. Expl. pi. 32, figs. 21-23. 1887. 
Zoarium consisting of very thin lamellate expansions, incrusting other objects. 
Cell apertures oblique, sub-triangular, diameter .30 mm.; irregularly dis¬ 
posed ; posterior margin very strongly elevated, oblique, angular. Surface 
with maculae, the centers of which are distant from each other about 5 mm.; 
the cells immediately adjacent and radiating from them, are larger and more 
