122 CONTRIBUTIONS TO CANADIAN PALAEONTOLOGY. 



Zaphrentis, sp. undetermined, Billings. 1863. Geology of Canada, p. 391. 

 Zaphrentis cinctosa, Billings. 1866. Cat. Sil. Foss. of Anticosti, p. 92. 

 Zaphrentis rugatula, Billings. 1874. Palseoz. Foss., vol. II., pt. I., p. 8, pi. 1, figs. 3, 3a. 

 Amplexus Shumardi, Rominger. 1876. Geol. Sur. Mich., Foss. Corals, p. 152, pi. 

 LIV., upper row. 



Represented in the collection of the Geological Survey by two speci- 

 mens (the types of Z. cinctosa) from the Clinton and Niagara formations, 

 one from Cockburn Island, Lake Huron, the other from near Owen 

 Sound. The general shape, manner of growth and structure of the coral- 

 lum leaves little doubt, at least in the mind of the writer, as to their 

 being referable to Milne-Edwards and Haime's species described from 

 specimens from the upper Silurian of Perry County, Tennessee. Rom- 

 inger's specimens are from the Niagara group of Drummond Island and 

 Point Detour, Lake Huron, and from Masonville, Iowa. 



The Canadian specimens may be described as follows : — Corallum sim- 

 ple, cylindrical, curved, and annulated at somewhat regular intervals by 

 distinct, prominent, angular ridges or frill-like expansions, from *5 to over 

 1 cent, apart, that represent periodic arrests of growth and the position 

 of former calyces ; reaching a length of over 8 cent, measured along the 

 convex curve and from 2 to 2*5 cent, in diameter at the summits of the 

 annular ridges. Epitheca striated transversely by fine lines of growth 

 crossing the well-marked longitudinal septal furrows at right angles, so as 

 to cause a cancellation of the surface. Calyx deep, with very steep, thin 

 enclosing side walls. Septa, in the neighbourhood of sixty, alternately 

 long and short, the former passing to or almost to the centre, the latter 

 poorly developed and very short ; in the catyx they ascend the sides as 

 low denticulated ridges, becoming gradually less prominent and more 

 rounded as the rim is approached. Tabulaa extending from wall to wall, 

 flexuous, irregular and turned down at the edge. 



Localities. — East side of Cockburn Island, 2 miles north of Mc- 

 Leod's Harbour, R. Bell, 1859; and in the township of Derby, lot 13, 

 concession 2, near Owen Sound, R. Bell, 1866 : in the Clinton and Niag- 

 ara formations. 



It is probable that the fossil occurring in the Guelph formation at 

 Hespeler and Guelph, Ontario, and referred by Nicholson (Palaaon. of 

 Ontario, 1875, p. 67) to Amplexus Yandelli, really belongs to this species. 



A comparison of the typss of Zaphrentis rugatula, Billings, with the 

 specimens from the above mentioned localities, Cockburn Island and 

 Owen Sound, reveals a similarity of form and structure that carries with it 

 a conviction that they are not separable specifically. The specimens of 

 Z. rugatula were collected at Cape Gaspe, Que., by Sir W. E. Logan in 

 Gaspe limestone No. 1, of whose age Mr. Billings in discussing the 



