MARYLAND GEOLOGICAL SURVEY. 227 



CHASMATOPORA SUBLAXA (Ulrich) 

 Plate XL, Figs. 7-10 



Phylloporina sullaxa Ulrich, 1890, Journ. Cincinnati Soc. Nat. Hist, vol. xii, 



p. 179, fig. 6. 

 Phylloporina sullaxa Ulrich, 1893, Geol. Minnesota, vol. iii, p. 209, pi. iv, 



figs. 1-7. 



Description. " Zoarium an undulating flabellif orm expansion, attain- 

 ing a diameter of 5 cm. or more, consisting of irregularly inosculating 

 slender subcylindrical branches, varying in width from 0.3 to 0.6 mm., 

 but averaging about 0.45 mm. Fenestrules large, subacutely elliptical, 

 varying considerably in shape and size, generally two or three time^ 

 longer than wide ; measuring longitudinally, the average number in 1 cm 

 is between five and six ; transversely, nine or ten in the same space. These 

 measurements apply to the Tennessee specimens. In the Minnesota form 

 of this species the fenestrules are smaller, averaging between six and 

 seven in 1 cm. lengthwise. 



" Reverse of the Tennessee specimens strongly rounded, nearly smooth, 

 or with faint longitudinal striae. In very young examples the latter 

 would probably be more distinct." Ulrich, 1893. 



Occurrence. CHAMBERSBURG LIMESTONE ( Caryocystites bed). Fort 

 Loudon and Blue Spring, Franklin County, Pennsylvania. 



Specimens from the Stones Biver, Black Eiver, and Chazyan rocks have 

 been identified with the types of this species which were found in the 

 Upper Stones Eiver limestone of Central Tennessee. 



Collections. Maryland Geological Survey, U. S. National Museum. 



Family ARTHROSTYLIDAE 



Genus HELOPORA Hall 

 HELOPORA DIVARICATA Ulrich 



Plate XL, Figs. 1-3 



Helopora divaricata Ulrich, 1886, Fourteenth Ann. Kept. Geol. Surv. Min- 

 nesota, p. 59. 



Helopora divaricata Ulrich, 1893, Geol. Minnesota, vol. iii, p. 191, pi. iii, 

 figs. 1-3. 



Helopora divaricata Bassler, 1911, Bull. U. S. Nat. Mus., No. 77, pp. 149-150, 

 text fig. 72. 



