lAMBE. J CANADIAN PALEOZOIC CORALS. 195 



about two inches or a little more ; width of cup from one inch to one 

 inch and a half ; depth about halt an inch." (Billings). . 



The largest specimen in the collection measures four inches along the 

 convex curve and two inches across the cup from the higher to the lower 

 side, other specimens are of all sizes from three-quarters of an inch in 

 length up. The epitheca is complete and generally well preserved. The 

 continuous laminar floor of the calyx in some specimens shows no trace 

 of the vesicular structure below, in others it is more or less blistered ; its 

 development at intervals as the corallum grew larger can be seen in a 

 number of specimens. 



Locality and formation. — Abundant in the Corniferous limestone of 

 Ontario. 



Genus Actinocystis, Lindstrom, 1882. 



Actim)cystis, Lindstrom. 1882. Of vers. Vet. Ak. Fhandl., XXXIX., No. 3, p. 21. 



Corallum simple, differing from Cystiphyllum only in the possession of 

 septa that are feebly developed more particularly in the base or toward 

 the centre. 



Type species. — A. {Cystiphyllum) Grayi, Milne-Edwards and Haime. 

 .ffaw^'e.— Silurian, Devonian. 



Actinocystis variabilis, Whiteaves. 



Cysteophyllum Aniericanwrn, var. arctioum, Meek. 1868. Trans Chicago Acad, of 

 Sciences, p. 80, pi. XI., figs. 6, 6a, 6b. 



Heliophyllum (like H. Halli), Billings. 1876. Rep. of Progress for 1874-75, Geol. Survey 

 of Canada, p. 68. 



CystiphyUum, Americanum, var. arcticwm, Whiteaves. 1891. Contr. to Can. Palseon. , 

 vol. I., pt. III., p. 206. 



Actinocystis variabilis, Whiteaves. 1892. Ibid, pt. IV., p. 271, pi. XXXV., figs. 3, 3a. 



Original description. — " Corallum simple strongly curved, varying in 

 shape from broadly turbinate and widely expanding, with the breadth at 

 the summit exceeding the height, to cylindro-conical and somewhat con- 

 tracted at the summit ; outer surface apparently almost smooth and 

 marked only with a few transverse wrinkles ; calyx rather deep, conical, 

 narrow at the base ; septa about eighty-five in number, extending from 

 the exterior to within a short distance from the centre, but feebly deve- 

 loped, thin, and rarely, if ever, quite straight, their regularity being fre- 

 quently disturbed by anchylosis with the walls of the interseptal vesicles. 

 Internal structure, apart from the septa, essentially the same as that of 

 Cystiphyllum and consisting exclusively of coarse vesicular tissue. The 

 vesicles are very large in the central area and diminish gradually in size 

 L-7i 



