404 Canadian Record of Science. 



length, when entire, and not far from seven inches in its 

 maximum height. 



Ottawa, October 9th, 1891. 



Note on the Occurrence of Paucispiral 

 Opercula of G-asteropoda in the G-uelph 

 Formation of Ontario 



By J. F. Whttbayes. 1 



Opercula of gasteropoda appear to be of rather rare 

 occurrence in the palaeozoic rocks of Canada. The best 

 known and earliest described are those of Maclurea Logani, 

 from the Black River limestone of Paquette's Rapids, on 

 the Ottawa River, which were first described and figured 

 by Salter in 1851, in the first decade of "Canadian Organic 

 Remains." The operculum of this shell, which has for- 

 tunately been found occupying its normal position in the 

 aperture of the shell to which it belongs, is in many 

 respects unlike that of any known gasteropod, whether 

 fossil or recent, both in its internal and external characters. 

 It was described by Dr. S. P. Woodward as " sinistrally 

 subspiral, solid, with two internal projections for the 

 attachment of muscles — one of them beneath the nucleus 

 and very thick and rugose." 



A specimen of another species of Maclurea, which has 

 since been described and figured under the name M. Mani- 

 tobensis, with its operculum in place, was collected by Prof. 

 H. T. Hind in the Trenton limestone at Punk Island, Lake 

 Winnipeg, but this operculum is very imperfect and badly 

 preserved. 



In 1874-82 several solid, calcareous and multispiral oper- 

 cula were collected by Mr. Joseph Townsend in the Guelph 

 limestone at Durham, Ont., but none of these were found 

 in situ. These opercula, some of which are described and 

 illustrated in a report on the fossils of the Guelph forma- 



1 Communicated by permission of the Director of the Geological Survey. 



