218 Systematic Paleontology 



the branches, apparently free from septa or tabulte, arranged in twelve 

 or thirteen vertical series; the apertures in adjacent series being more 

 or less irregularly alternate. Because of the obliquity of the corallites, 

 their apertures are elliptical, the peripheral borders regular, subangular. 

 The diameter of the branches is from 2 mm. to 3.5 mm. with six or seven . 

 corallites occupying a space of 5 mm. longitudinally." Weller, 1903. 



Occurrence. — Helderberg Formation, Keyser Member. Near Cum- 

 berland. Between the Bryozoan subzone and the overlving Stromatopora 

 bed (tide Ul rich). 



CoJleciion. — U. S. Xational ^luseum. 



Genus PLEURODICTYUM Goldfuss 



Pleurodictyum lenticulare (Hall) 



Plate XXVI, Fig. 1. 



Michelinia lenticularis Hall, 1874, 26th Rept. N. Y. State Mus., p. 113. 

 Michelinia lenticularis Hall, 1879, 32d Rept. N. Y. State Mus., p. 145. 

 Michelinia lenticularis Hall, 1883, Rept. N. Y. State Geol. for 1882, pi. ill, figs. 



1, 2, 3, 5. 

 Michelinia lenticularis Hall, 1887, Pal. N. Y., vol. vl, p. 7, pi. iii, figs. 1, 2, 3, 5. 

 Pleurodictyum lenticulare Beecher, 1891, Trans. Conn. Acad., vol. viii, p. 



207. 



Description. — Corallum comjjound, consisting of short, closely united, 

 polygonal corallites. Outer walls of corallites perforate. Calyx shallow, 

 septa consisting of spines varying in size, arranged in lines on sides of 

 calyx and irregularly clustered in center. Number of septa not clearly 

 determinable, apparently nearly 20. The walls of calyx perforated by 

 irregularly placed pores, about 0.2 inni. in diameter. In the specimen 

 observed the corallites number 1(! and the corallum is attached at base to 

 shell of a brachiopod. 



Diameter of corallites 5 to 6 mm., length approximately the same. 



This species was named Michelinin Iciiticiihtris- by Hall who did not 

 satisfactorily determine its intimate structure. It is not a species of 

 Michelinia and lacks the distinctive features of that genus. It was 

 correctly referred to the genus Pleurodictyum by Beecher. 



Occurrence. — Helderberg Formation. Coeymans Memri-i;. Warren 

 Point, Pennsylvania. 



Collection. — Marvland Geological Survev. 



