80 PALEONTOLOGY OF NEW YORK. 



oblique than the others ; the posterior or upper portions of the walls are 

 exposed for nearly their entire length, being more or less distinctly carinate. 

 There are slightly elevated, transverse ridges between the larger cells, giving 

 to the macula} a geometrical appearance. 



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



LiCHENALIA OVATA. 



PLATK XXXn, FIGS. l-«. 



LicAenalia ovata, Hall. Report of State Geologist for 1885. Expl. pi. 32, figs. 1-5. 1887. 



ZoARiuM consisting of lamellate expansions, free or encrusting. Thickness of 

 specimens observed 2 mm. Cells tubular, cylindrical, at right angles to the 

 surface ; septa wanting. Apertures broadly ovate and sometimes trilobate, 

 length .40 mm., width three-fourths the length ; radiating from maculae. 

 Posterior margin of peristomes strongly elevated, oblique, frequently with two 

 slight denticulations. Surface with substellate maculas destitute of cell aper- 

 tures, the centers of which are distant from each other about 5 mm., diame- 

 ter 2 mm. ; adjacent apertures not larger than the others. Intercellular 

 space regularly septate, septa distant. 



This species closely resembles L. suhsfellata, but may be distinguished by its 

 larger, more ovate cell apertures, and the ab.sence of septa in the cell tubes ; 

 from Lichmalia (Odoniofri/pa) alveata by its less closely arranged, ovate cell aper- 

 tures, well defined apertural margins, and its thicker fronds. 



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



LiCHENALIA ALTERNATA. 



PLATE XXXI, FIGS. 39-41. 



Liehaudia aUfmnta, Hall. Trans. Albany Institute, vol. x, abstract, p. 8. 1881. 



Report of State Geologist for 1885. Expl. pi. 31, figs. 39-41. 1887. 



ZoARiUM consisting of very thin lamellate expansions, incrusting other objects. 

 Cell apertures oval, length about .35 mm., width from one-half to two-thirds 

 the length ; closely disposed, frequently alternating and sub-imbricating. Pos- 



