78 PALEONTOLOGY OF NEW YORK. 



tions though very narrow frequently preserve the crescentic appearance com- 

 mon to the denticulations of many other species. The gradation through 

 various species from this form of denticulation to the wide crescentic form is 

 very gradual. Many specimens have been examined, but I have been unable 

 to discover the accessory cells mentioned by Mr. Ulrich as constituting a dis- 

 tinctive character. 



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



LiCHENALIA LUNATA, var. TDBULATA. 



PLATE XXXI, FIGS. 28, 29. 



Liehendlia lunata, var. tubulata. Hall. Report of State Geologist for 1885. Expl. pi. 31, figs. 28, 29 1887. 



This associated variety differs from ordinary forms of L. lunata, in its tubular 

 mode of growth. 



LiCHENALIA SCBSTELLATA. 



PLATE XXVI. FIG. 26 ; AND PLATE XXX, FIGS. 1-11. 



lAchenalia svbgtellata, Hall. Trans. Albany Institute, vol. x, abstract, p. 7. 1881. 



" " " Report of State Geologist for 1882. Expl. pi. 24, fig. 26. 1883. 



" Report of State Geologist for 1885, advance sheets. Expl. pi. 30, figs. 1-11. 

 1886. 

 7 PUtvMjxyra normalis, Ulrich. Cont. Am. Pal., vol. i. No. 1, p. 20. 1886. 



ZoARiUM consisting of lamellate expansions, or of masses formed by the super- 

 imposition of successive layers of irregular growth, frequently contorted. 

 Cells cylindrical, usually at right angles to the surface ; septa infrequent 

 or wanting. Cell apertures circular, diameter .33 mm. ; closely and 

 irregularly disposed : peristomes strong, generally the posterior portion is 

 the more distinctly elevated, oblique, and occasionally denticulated. Sur- 

 face marked by flat or slightly elevated substellate non-celluliferous maculae, 

 the centers of which are distant from each other about 4 mm. The 

 apertures immediately adjacent to these are radiatingly disposed, larger and 

 more oblique than on other portions of the frond. Intercellular space, near 

 the base, occupied by irregular vesicles, above by septate tubuli ; from five to 

 eight septa in the space of 1 mm. Occasionally the apertures are operculate, 



