PAL.-EONTOLOGY. lox 



drical form ; the others, feebly attached stems, by breaking loose 

 and falling into any accidental position, were obliged to alter the 

 direction of their calyces, and if by subsequent currents or other 

 causes their position was changed, they had to accommodate them- 

 selves again to the new position, and this, I suppose, is the true 

 reason of their distorted growth. The calyces of the polyp cells are 

 deep, gradually tapering, with inclined suberect margins. Lamellre 

 delicate, linear, subequal near the margin, crenulated at the edges, 

 and obtusely carinated on the side faces. Apertural gap well 

 marked. Interlamellar interstices of the peripheral area filled with 

 vesiculose plates. Central area traversed by compound vesiculose 

 diaphragms, which are much intersected by the vertical lamellae. 

 Diameter of large calyces from five to six centimeters. Number of 

 lamellae in calyces four centimeters wide, 112. Found in the upper 

 shaly strata of the Hamilton group, at Partridge Point, Thunder 

 Bay. 



Plate XXXVI. — Lower figure represents the peculiar mode of 

 growth of the polyp cells. Some specimens found at Widder, C. W., 

 in the Hamilton group, are of entirely similar growth, but these 

 evidently are only a modified form of Cyathophyllum Hallii, with 

 obscure lateral carinae. 



CYATHOPHYLLUM HOUGHTONI, N. Sp. 



Erect, conico-cylindrical polyp cells, with a strong latero-basal at- 

 tachment. Surface obtusely wrinkled, rarely interrupted by acute 

 annulations. Calyx deep, with steep side walls, and erect, slightly 

 dilating edges. Bottom of cells about one third as wide as their 

 outer margin, subplane or gently convex, with depressed circum- 

 ference, crossed by the lamellae, of which three or four are always 

 much stouter than the others and coalesce in the centre. Some- 

 times the centre of the cell bottoms is depressed, with a ring-like 

 elevation surrounding the depression, of smooth surface. Lamellae 

 alternately larger and smaller, linear near the bottom of the calyces, 

 roof-shaped on the ascending walls, and frequently explanate into a 

 blistered plicated membrane near the margins. The surface and the 



