Scolithus in Rocks. 305 



In the examination of the measures of the Chazy forma- 

 tion about Ottawa, however, the writer has observed nume- 

 rous scolithoid remains from strata newer than those at 

 L'Anse au Loup or at Ste. Anne's, Beauharnois, &c. 



At the Hog's Back, Nepean, in the county of Carleton, 

 Ont., about three miles from Ottawa city, the Chazy forma- 

 tion crops out in the shape of a partially denuded anticlinal, 

 exhibiting on the eastern side of its axis a considerable 

 thickness of strata consisting of sandstones, sandy shales 

 with calcareous matter, and limestones, given in their 

 natural and stratigraphical sequence from the base up. 

 Some of the shales in the exposure are decidedly argillace- 

 ous in character, and hold abundance of a species of Lin- 

 gula — the L. Belli (Billings). This band marks a well 

 defined zone in our Chazy formation, and is referred to as 

 the zone of Lingula Belli (see Geol. Eep. Trans. 0. F. N. C, 

 1885-1886.) Above this zone, and a few feet above the 

 Scolithus horizon, the "Leperditia band" occurs here in its 

 normal condition, as described by Sir William Logan and 

 Mi*. Billings in the publications of the Geological Survey of 

 Canada at various dates, so that the intermediate beds of 

 an arenaceous nature, on careful examination, are seen to 

 contain abundance of a species of Scolithus differing but 

 little, if any, from the true S. Canadensis (Billings). The 

 characters of this last agree admirably with the form of 

 those from Hog's Back, although there is no doubt what- 

 ever as to the age of the series in question being Chazy. 



The second place where the genus in question has been 

 observed is at Britannia, Ont., near the southern shores of 

 Lake Des Chenes, on the Ottawa River, six miles west of 

 Ottawa city. There at Britannia, some four hundred yards 

 south-west of the railroad crossing or station, numerous 

 remains of a species of Scolithus were collected on the 

 occasion of the excursion of the Field Naturalists' Club, in 

 September, 1885. On finding it, the question arose, and 

 has since formed the subject of a slight controversy, as to 

 whether or not the rocks there were really Chazy, or that 

 on account of the occurrence of these annelid (?) burrows, 

 the rocks ouecht to be ascribed to the aa;e of the Potsdam 



