.] CANADIAN PALEOZOIC CORALS. 79 



HELIOPORID^E. 



Genus Heliolites, Dana, 1846. 



(Wilkes's Expl. Exped. Zooph., p. 541.) 



Corallum discoidal, hemispherical or pyriform, sometimes in explanate 

 masses, at times ramose, composed of parallel, more or less distant, 

 cylindrical coraliites that emerge at right angles to the surface in gene- 

 rally slightly exsert calyces ; spaces between the coraliites filled with 

 numerous, intimately united, polygonal tubules parallel to the coraliites 

 and of the same length ; walls of the tubules thin, regular ; septa twelve 

 in number, of equal size, sometimes reaching the centre of the visceral 

 chamber, not present in the tubules; tabulae numerous, horizontal, regu- 

 lar, occurring both in the coraliites and tubules ; epitheca covering the 

 base. 



Heliolites interstincta, L. (Sp.) 



Plate IL, figs. 6, 6a. 



Madrepora interstincta, Linne. 1767. Syst. Nat., ed. 12, p. 1276. 



Heliolites interstincta, Milne-Edwards and Haime. 1851. Polyp. Foss. des Terr. 

 Pakeoz., p. 214. 

 n n Milne-Edwards and Haime. 1855. Brit. Foss. Corals, p. 249, 



pi. LVIL, figs. 5, 5a-d. 

 M i, Nicholson. 1875. Palaeon. of Ont., p. 51. 



Heliolites inter stinctus, Rominger. 1876. Geol. Sur. Mich., Foss. Corals, p. 11., pi. 



L, fig. 1. 

 Heliolites interstincta, Nicholson. 1880. Sil. Foss. of Girvan, pp. 57 and 254, pi. XVI., 

 figs«. 1 — 4. 



Corallum generally irregularly hemispherical or discoidal with a more 

 or less convex upper surface, attached by the centre of the basal surface, 

 which usually exhibits concentric foldings or ridges of growth and is 

 protected by an epithecal covering; attaining a diameter of nearly 7 

 inches with a height of about 3 inches. In its initial stages the 

 corallum is of a pyriform or subspherical shape. Coraliites proceeding 

 radially from the basal beginning and issuing at right angles to the 

 surface ; they are from 1 to 3 mm. apart, circular, averaging 1 "5 mm. in 

 diameter and showing little variation in size in the same specimen. The 

 spaces between the coraliites are occupied by numerous polygonal 

 tubules, parallel to the coraliites, from -25 to -33 mm. in diameter in 

 different specimens, there being from three to twelve tubules in a straight 

 line between adjacent coraliites. The horizontal tabulae of the coraliites 

 are rather regular in disposition, from three to four occurring in a 

 space of 1 mm. The tubules have tabulae similar to those of the coral- 



