186 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



extension, above whose upper surface rises abruptly a central calicular 

 area about one-fourth the breadth of the corallum j attaining a breadth 

 of over 19 cent, and a thickness at the centre of about 4 cent. Height 

 of the central part enclosing the calyx, above the level of the surrounding 

 surface, in large individuals, from about 1*5 to 2 cents. Calyx * about 

 twic^ as wide as high, with a diameter of about one-tenth the breadth of 

 the corallum, flat at the bottom and with very steep sides. Septa, in the 

 visceral chamber, lamellar, of two orders, primaries and secondaries, 

 alternating, the former meeting at the centre with a slight amount of 

 twisting, the latter not quite half the length of the former ; ascending 

 the sides of the calyx as sharp edged lamellae they pass down and ove r 

 the extracalicular surface as gradually broadening, flatly convex, radiat- 

 ing ridges having a maximum breadth near the periphery of 7 mm, ; they 

 number in different individuals from about seventy-four to eighty-four. 

 Well developed flat or concave tabuke, turned down at their edges and 

 as broad as one-half the width of the calyx, are seen in a radial section, 

 beneath the bottom of the cup. The whole of the upper surface is marked 

 by fine, raised, interrupted and concentric, ripple-like growth lines, 

 generally less than 1 mm. apart, those of one septal ridge sometimes con- 

 tinuous with, at other times alternating with those of adjacent ridges ; the 

 basal surface presents a similar appearence except that here the septal 

 radii are concave instead of being convex. The structure of the walls of 

 the calyx and of the extended frill-like margin appears to be very dense. 

 In radial sections the gradual growth of the corallum outward is indi- 

 cated by parallel lines approximately at right angles to, and joining the 

 ripple-like markings on, the upper and lower surfaces. In vertical tan- 

 gential sections the septa are seen to be made up of superimposed convex 

 layers resembling the septal structure of C. Magnijicum, Billings, but 

 denser. 



" Locality. — South-west Point, Anticosti, division IV. of the -Anticosti 

 group, collected by J. Richardson, 1856." (Lambe, 1899.) 



Chonophyllum Belli, Billings. 

 Plate XVI., figs. 5 and 6. 



Chonophyllum Belli, Billings. 1865. Canadian Naturalist, new series, vol. II., p. 431. 



Corallum at first short and broader than high, with a deep calyx having 

 broadly expanded generally reflexed margins, with age increasing in 

 height and assuming a subcylindrical form by the superaddition of 

 successive invaginated calycinal expansions ; type specimen 7 cent, 

 in height, slightly over 3 cent, in average breadth, pointed at the base. 



* Originally described as the basal centre ' ' excavated into a cup-like cavity. " 



