182 Dr. II. A. Nicholson on neto Species of Polyzoa 



6. Fcnestella nervata, Nich. PI. XIV. figs. 6, G a. 



Frond fan-shaped (?), coni])Osed of narrow, closely approx- 

 imated branches, about four or five of wliich occupy the .space 

 of one line. On the non-celluliferous side of the frond are 

 two strong, slightly diverging, rounded ribs, about half a line 

 in diameter, like the midribs of a midticostate leaf. From the 

 sides of these ribs the branelies sj)ring oblicpiely, being directed 

 in ojiposite directions on opposite sides of the rib, with which 

 they make a very acute angle (10° or less). Fcnestrules long 

 and narrow, nearly twice as long as wide, about three in the 

 space of one line measured vertically, and about five in the 

 same space measured transversely. For the most part the 

 fcnestrules do not alternate in contiguous rows, but are placed 

 opposite one another. Tlie narrow rounded dis.sepiments 

 are thus also placed nearly or quite o])posite to one another. 

 Branches faintly striated in a longitudiiud direction. Cellu- 

 liferous side unknown. 



The only example of this species that I have seen is im- 

 perfect, and the ribs from which the branches rise are placed 

 two lines apart near the base, and four lines apart near the 

 summit. It would seem most probable that the ribs sprung 

 from a common root, and that there were many of them in the 

 perfect frond. The species is distinguished not only by the 

 possession of these ribs, but also by the long naiTow fcnestrules, 

 which are not placed alternately, but so disposed that the 

 dissejiiments connecting contiguous branches become opposite 

 or subopposite. 



Locality and Formation. — Summit of the Niagara Forma- 

 tion (in beds probably the equivalent of the Guelph Forma- 

 tion of Canada), Cedarville, Southera Ohio. Collected by 

 Prof. Edward Orton. 



7. Ceramopora ohioensis^ Nich. PI. XIV. figs. 7-7 d. 



Polyzoary incnisting, forming thin expansions attached to 

 the surface of Brachiopods and Corals, and consisting, typi- 

 cally at any rate, of a single layer of oblique cells. Cells 

 arranged in intersecting diagonal lines, and disposed in a 

 somewhat concentric manner found more or fewer central 

 points ; their upper walls thin and arched ; the cell-mouths 

 oblique and, when most perfect, semicircular in shape. About 

 eight cells in the space of one line. 



Such are the appearances presented by this fossil when 

 quite perfect ; and' its examination in this condition leaves 

 little doubt as to the propriety of placing it in Hall's genus 



