Maryland Geological Survey 285 



Genus SEMICOSCINIUM Prout 



Semicoscinium planum n. sp. 

 Plate XLV, Fig. 7 ; Plate XLIX, Fig. 4 



Description. — Form of entire zoarium unknown but probably infundi- 

 buliform, the type and only specimen seen being a fragment showing the 

 reverse and consisting of a fan-shaped slightly undulated expansion about 

 3.5 cm. both in height and -width. Branches strong on the non-cellulif- 

 erous side, varying slightly in width, flattened and sometimes even 

 slightly concave, about 8 in 1 cm. Dissepiments rather short, on the same 

 plane with the branches ; fenestrules elongate, oval. Celluliferous side 

 known only from thin sections which show that the zooecia are in two 

 rows, open directly upward, have well-marked peristomes, and are sepa- 

 rated by an elevated carina slightly flexuous and considerably expanded 

 at the top; zooecial apertures circular about two-thirds their diameter 

 apart, 8 in 2 mm. and 4 to a branch. 



The rather large, elongate fenestrules, plane, fiat, reverse and expanded 

 carina with its concave surface distinguish this species from associated 

 forms of the Fenestellida?. 



Occurrence. — liELOERBEUG Formation, Keyser Member. Hyndman, 

 Pennsylvania. 



Collection. — U. S. National Museum. 



Semicoscinium coronis (Hall) 

 Plate LI, Figs. 3-5 



Fenestella Coronis Hall, 1883, Thirty-second Ann. Rept. N. Y. State Mus., p. 



171 (reprint, 1880, p. 33). 

 Fenestella Coronis Hall and Simpson, 1887, Pal. N. Y., vol. vi, p. 51, pi. xxi, 



figs. 10-13. 



Description. — A detailed description of this fine species has been given 

 by Hall and Simpson. The prominent expanded carina; on the cellu- 

 liferous face and the quadrangular form of the fenestrules on the reverse 

 are the most noticeable features of the species. 



Occurrence. — Helderberg Formation, Xew Scotland Member. 

 North foot of Moore Knob, Washington County. 



Collection. — U. S. National Museum. 



