Martlaxd Geological Survey 283 



which project laterally from the sides of the carinae over a fenestrule or on 

 a dissepiment. These probably represent a peculiar kind of ovicell. 



The presence of semicircular ovicells (?) on the sides of the carinae 

 suggests the advisability of referring this fine species to the otherwise 

 Middle Devonian genus Cycloporina Simpson/ Undoubtedly F. alti- 

 dorsata is a true progenitor of the type of Cycloporina, but it is also 

 true that it is readily distinguished from that species by characters which 

 in a future and already much needed revision of the Fenestellidae might 

 be deemed of generic and not merely specific importance. Pending such 

 investigation the relationship of this early Devonian species seems to be 

 sufficiently indicated by the form of the name adopted above. No Helder- 

 berg species is likely to be confused with it. 



Occurrence. — Helderbeug Formation, Keyser ]Member. Devil's 

 Backbone. Abundant. 



Collections. — -Maryland Geological Survey, U. S. Xational Museum. 



Genus POLYPORA McCoy 

 POLYPORA DICTYOTA n. Sp. 



Plate XLVII, Fig. 3 



Description. — Zoarium an undulating or flat, fan-shaped expansion, 

 the largest specimen seen although fragmentary measuring 4.5 cm. in 

 height. Branches slender, about 11 in 1 cm. and varying slightly in 

 width; surface minutely granulose, the granules sho^ving best in thin 

 sections. Dissepiments short, depressed, varying from about one-half the 

 width of the branch in the lower portion of the zoarium to the entire 

 width in the upper and less crowded parts. Fenestrules varying from sub- 

 rhomboidal to quadrate. Zooecia arranged in two or three ranges, the 

 latter number predominating. Zooecial apertures 10 in 2 mm., -1 to a 

 branch. Eeverse of both branches and dissepiments rounded and faintly 

 granulose. 



^ Simpson. Handbook Genera North America. Pal. Bry. in 14tli Rept. State 

 Geo!. N. Y. for 1894, p. 504, 1895. 



