28 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



inner sides of the corallites near the surface, and in one corallite this 

 ridge is opposite to two ridges in the outer wall. 



Niagara formation. — Thorold, Ont., collected by E. Billings. 



Coznites lunata, Nicholson and Hinde. 



€cenites lunata, Nicholson and Hinde. 1873. Canadian Journal, new series, vol. XIV., 

 p. 151, figs. 2a, b, c. 

 .. .. Nicholson. 1875. Palseon. of Ont., p. 55, figs. 25a, b, c. 



" Corallum forming a thin crust, apparently about two-thirds of a line 

 in thickness. Calyces strongly curved, crescentic or lunate, their form 

 being due to the projection into their cavity of a single strong rounded 

 tooth developed from the concave lip. Calyces about one-fourth of a line 

 in their long diameter, and one-eighth of a line across ; eight in the space 

 of two lines. Corallites perpendicular to the surface, appearing as if 

 embedded in a dense ccenenchyma, though this is most probably due 

 simply to the great thickening of their walls." (Nicholson and Hinde.) 



Niagara formation. — Owen Sound, Ont., J. Townsend, 1874; north 

 end of Lake Temiscaming, Que., R. Bell, 1887; and the "Jumpers" 

 Anticosti. 



Cgenites Selwynii, Nicholson. (Sp.) 



(Plate L, figs. 4, 4a.) 



Alveolites Sehvynii, Nicholson. 1874. Geological Magazine, new series, vol. I., p. 15, 

 fig. 3; 1874, Paljeon. of Ont., p. 56, fig. 15, plate VII,, fig. 4. 



Corallum in the form of a thinly incrusting expansion about 2 mm. thick 

 with a thin basal epitheca. Corallites flattened throughout their length, 

 prostrate and by a sudden upward bend debouching at right angles, or 

 with only a slight obliquity to the surface j average breadth slightly over 

 1 mm., average height *25 mm. Walls of the corallites thin, except at the 

 surface, where they are greatly thickened, causing the calyces to have the 

 form of narrow slits. Calyces more or less curved, sometimes straight, 

 about 2 mm. long and -25 mm. wide with thick rounded margins and a 

 broad not very distinct lip on the concave side of the opening ; a depressed 

 line surrounding the calyces defines the outer limits of the corallites. 

 Tabulae complete, distant. Mural pores of medium size, placed about 1 mm. 

 apart in the narrow edges, but also occurring irregularly in the broad sides 

 of the corallites. The epitheca is finely striated in a direction at right 

 angles to the length of the corallites. The calyces are sometimes quite 

 straight, but it is usual to find them either evenly curved backward or 

 else bending backward at either end ; they are about 1 mm. in advance of 

 each other and overlap laterally. 



