UMBE. J CANADIAN PALAEOZOIC CORALS. 99 



of considerable size interspersed with much smaller ones, in others they 

 are uniformly rather large, or they may be small with little disparity in 

 size. 



The coral from Snake Island, Lake St. John, Que., (Hudson River 

 formation), described by Billings under the name C. Blainvilli, is here 

 referred to this species, from which it was separated specifically on account 

 of the supposed smaller size of its corallites. It does not differ, however, 

 in this respect from specimens of C. alveolaia, Goldfuss, in which the cor- 

 allites are rather below the average in size. In the Lake St. John speci- 

 men the corallites have an average diameter of 3 mm., but are sometimes 

 nearly i-5 mm. in diameter, the septa are alternately large and small and 

 number about twenty-four. The tabulae as well as the septa are identical 

 in shape and disposition with those of C. alveolaia. 



As has already been stated, the tabulae are generally deflected at the 

 margin, but in some specimens they are less depressed where they touch 

 the septa than they are between them, causing the tabulse to have a 

 crinkled or plicated appearance near their edges, a not uncommon develop- 

 ment in some species of Favosites. 



Rominger mentions (op. cit. p. 90) the occurrence of this species in 

 rocks of Niagara age at Point Betour, Lake Huron. 



Hudson River formation. — North Point, Drummond Island, Lake 

 Huron, J. Richardson, 1847 ; Cape Symth, Lake Huron, R. Bell, 1859 ; 

 Credit River at StreetsvUle, Ont., J. B. Tyrrell, 1888 ; Snake Island, 

 Lake St. John, J. Richardson, 1857; English Head, Anticosti, J. Rich- 

 ardson, 1856. 



Trenton formation. — East Selkirk and Lower Port Garry, Manitoba, 

 R.Bell, 1880, A. McCharles, 1884, L. M. Lambe, 1890; Jack Head 

 Island, Lake Winnipeg, D. B. Bowling and L. M. Lambe, 1890; Mark- 

 ham Lake, Telzoa River, Bistrict of Mackenzie, (lat. 62° 44', long. 103°), 

 J. B, Tyrrell, 1893. 



In 1896, Br. R. W. Ells and the writer found, at Stewart's quarry (near 

 Sand Point), lot 18, concession 11, township of McNab, Renfrew county, 

 Ont., in the Black River limestone, specimens of C. alveolata, Goldfuss, 

 and C. Haiti, Nicholson, in situ, within a few feet of each other. The 

 writer is not aware that G. alveolata, Goldfuss, has previously been 

 recorded in Canada or the United States from as low a horizon as the 

 Black River limestone. A transverse section of the corallites of the 

 specimen from Stewart's quarry is shown on plate VI. 



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