150 CONTEIBUTIONS TO CANADIAN PALEONTOLOGY. 



their regularity by the inner ends of the sepia, confined to a central zone 

 varying in breadth from about one-fourth to one-third of the entire dia- 

 meter of the coral] um. Vesicles filling the septal interspaces outside the 

 tabulate zone, small, strongly curved with their convex sides upward, 

 resting on each other and against the sides of the septa, their general 

 direction being upward and outward at right angles to that of the arched 

 carinas of which they are independent in their disposition. 



Locality. — Abundant in the Corniferous and Eamilton formations of 

 Ontario. 



Cyathophyllum tenuiseptatum, Billings. (Sp.) 



Heliophyllum tenuiseptatum, Billings, 1859. Canadian Journal, new series, vol. IV., 



p. 126. 

 Gyathophyll/um juvene, Rominger, 1876. Geol. Sur. Mich., Foss. Corals,^ p. 100, pi. 



XXXV. , three specimens in upper row. 

 Heliophyllum elegantulum, Nicholson, 1876. Proc. Royal Soc. Edinburgh, p. 150 ; and 

 1889, Manual of Palieon., p. 289, figs. 168A and B. 



Dr. Rominger succinctly describes this species in his remarks on 

 Cyathophyllum, juvene as follows — " A very constant form found in asso- 

 ciation with the preceding species {^Heliophyllum Halli), resembling it in 

 all particulars, but in all proportions smaller. The arched carinae are 

 closely approximated, twenty-four on the space of a centimeter. Number 

 of lamellae from sixty to seventy in the circumference of calyces two and 

 one quarter centimeters wide, which is about the largest size observed." 



Locality. — Found in the Hamilton formation in Ontario. 



Dr. Rominger records its occurrence also in the Upper Helderberg 

 strata of New York, Ohio and Kentucky. 



Cyathophyllum exigdum, Billings. (Sp.) 



Heliophyllum exiguum, Billings, 1860, Canadian Journal, new series, vol. V. , p. 261, 



figs, 9 and 10. 

 Petraia Logani, Nicholson, 1874. Palseon. of Ont., p. 30, pi. III., figs 3, Za-f. 

 Petraia(?) Logani, Nicholson, 1875. Canadian Naturalist, new series, vol. VIZ., p. 143. 

 Zaphrentis exigua, Rominger, 1876. Geol. Sur. Mich., Foss. Corals, p. 149, pi. LIII. 

 Heliophyllum exiguum, Hall, 1876. Illus. Dev. Fose., pi. XXXII, figs. 1-4. 



Corallum simple, small, conical, slighly curved, pointed below, flattened on 

 the side of the convex curve, near the base ; varying in size from about 20 

 mm. long, measured on the convex curve, by about 15 mm. across the top of 

 the cup, to as large as 30 mm. by 26 mm. Epitheca complete. Outer surface 

 showing coarse transverse ridges of growth with minor growth lines 

 between, and longitudinal septal furrows with the cardinal and alar septa 

 generally clearly indicated. Calyx moderately deep, rather oblique, often 



