Upper Helderherg Group, 



153 



tially closing the apertures, giving them an acutely semielliptical form 

 of one mm. in length ; margins of apertures not elevated, space be- 

 tween apertures angular, striated ; at base of each aperture slight node; 

 surface sometimes presenting a distinctly reticulated appearance. 



Locality — Falls of the Ohio river. 



LiCHENALIA LONGISPINA, 71. sp. 



Lamellate, cell-apertiires oval, length .35 mm. irregularly disposed; 

 between adjacent apertures, thin, sharp elevations, uniting and form- 

 ing polygonal areas, which sometimes have a height of one mm., at 

 the angles of the elevations are strong spines, one mm. in length. 



Locality — Falls of the Ohio river. 



LiCHENALIA CIRCIls^CTA, n. Sp. 



Foliaceous ; cells oblique, diameter of apertures .20 to .%o mm., 

 margins unequally elevated, one portion strongly elevated, extending 

 over and constricting the aperature, bidenticulated, between apertures 

 are thin, oblique elevations, uniting, forming polygonal elevations 

 around the apertures; maculae distant four mm., centers without ap- 

 ertures ; cells radiating, larger than the others ; the more oblique the 

 cells, the less conspicuous the elevations. 



Locality — Falls of the Ohio river. 



LlCHENALIA COMPLEX A, 5jt?. 



The manner of growth of this species is the same as that of L. air- 

 cincta, but the apertures are larger and at a greater distance apart, 

 the enclosing walls are stronger, the frond presenting a much stronger 

 appearance, the polygonal elevations have very much the appearance 

 of the cell mouths of a Favositc, and without a close examination 

 might be mistaken for them. 



Locality — Onondaga Valley, N. Y. 



LlCHEIs^ALIA GRANIFERA, n. Sp. 



Foliaceous; cell-apertures usually oblique to surface, oval or sub- 

 triangular, length .33 mm., margins sometimes equal, at other times 

 the upper portion of cell- wall exposed more than the length of aper- 

 ture, irregularly disposed; maculae not elevated, centers distant four 

 mm., without apertures, cells radiating from centers, intercellular 

 space with promment granules, cell walls very fragile, margins usually 

 bidenticulate ; interior intercellular space vesiculose. 



Locality — Falls of the Ohio river. 

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