154 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



verse sections the line of division between the walls of adjacent corallices 

 is well shown. Calyces moderately deep, their depth being about equal 

 to or somewhat more than half their diameter, flat at the botttom, their 

 sides steep with well defined septa of two sizes, the larger of which reach 

 the middle of the bottom ; marginal junction of contiguous calyces 

 sharply angular. Septa from thirty to fifty in number, alternately long 

 and short, the longer extending to the centre, the others less than half 

 that length, carinated on their sides. Tabulae about one-half the 

 width of the diameter of the corallite, flat or concave, irregular, 

 inclined to become vesiculous, bounded exteriorly by a narrow zone of 

 rather small, outwardly ascending, curved dissepiments between the 

 septa. 



In describing C. arcticum, from the Mackenzie River basin, Meek 

 notices the resemblance of his specimens to C. quadrigemiinum^ 

 Goldfuss. In the figures of C. quadrigeminum in the Petrefacta 

 Germanise two sizes of septa are clearly shown as well as both interstitial 

 and calycinal gemmation. 



Genus Ckepidophyllum, Nicholson and Thompson. 1876. 



Crepidophyllum, Nicholson and Thompson. 1876. Proc. Royal Soc. Edinburgh, vol. 

 IX., p. 149. 



Corallum aggregate, formed of cylindrical corallites that grow upward 

 close together or touching each other, or else connected by periodic ex- 

 pansions constituting a series of horizontal floors. Increase by marginal 

 calicinal gemmation. Epitheca complete. Septa well developed, strongly 

 carinated, the inner ends of the primaries combining to form a narrow 

 axial tube which is sometimes open longitudinally on the side of the septal 

 fossette. Tabuhe confined to the central tubular area. Vesicular zone 

 broad, surrounding the tabulate area. 



Type species. — C. (Diphyphyllum) Archiaci, Billings. 



Range. — De vo nian. 



Crepidophyllum Archiaci, Billings. (Sp.) 



Plate XIIL, figs. 1, la. 

 % 



Diphyphyllum Archiaci, Billings. 1860. Canadian Journal, new series, vol. V., p. 260, 



%. 8. 

 Heliophyllum sub-ccespitosum, Nicholson. 1874. Geological Magazine, new series, vol. 

 I., p. 58, pi. IV., fig. 9 ; and Palaeon. of Ont., p. 27, fig. 5. 

 Diphyphyllum Archiaci, Nicholson. 1875. Palseon. of Ont., p. 74, fig. 41. 



" " Rominger. 1876. Geol. Sur. Mich., Foss. Corals, p. 125, pi. 



XL VII., upper row and right half of lower row. 



