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CONTRIBUTIONS TO A FAUNA CANADENSIS ; 



BEING AN ACCOUNT OF THE 



ANIMALS DREDGED IN LAKE ONTARIO IN 1872. 



BY H. ALLEYNE NICHOLSON, M.D., D.Sc., JLA., F.K.S.B., 



Professor of Natural History in University College, Toronto. 



The present paper is intended as a sni^plement to the " Preliminarjr 

 Report on Dredgings in Lake Ontario," which I have already had the 

 honour of submitting to the G-overnment of the Province of Ontario. 

 In that paper I gave a brief account of the results which were obtained 

 in the dredgings which I carried out in the summer of 1872 under the 

 allspices of the Ontario Government. I now purpose to describe more 

 fully the animals obtained in these dredgings; bu.t, before commencing- 

 the actual description of these, it may be as well to repeat the descrip- 

 tion given in the Report already referred to (Annals and Magazine of 

 Natxiral History, October, 1872,) of the natiire of the bottom of the 

 lake at various depths. 



The dredgings were all carried on in the later part of June and the 

 early part of July, and were made partly from the yacht "Ina" and 

 partly from the steamer "Bouquet." They were entirely carried 

 on by hand, and the dredges and rope were such as are ordinarily 

 employed in deep-sea dredgings. In dredging in deep water, however, 

 a bag of embroidery canvas was attached outside the ordinary net — 

 an addition rendered necessary by the exti'emely fine nature of- the 

 mud at great depths. Even with this precaution, the dredge not 

 unfreqTiently came up empty from great depths, all the finer portions 

 of its contents having been washed out. In deep water-, also, a fifty- 

 six pound weight was attached to the rope about twelve feet above 

 the dredge ; and the same was necessary in shallow water, where the 

 weeds were very thick, in order to secure that the dredge should 

 reach the actual bottom. 



The dredgings were all carried on within a radius of ten miles from 

 Toronto; and the following will show the general nature of the bottom. 



