1917] The Ottawa Naturalist. 79 



the broken ends of his ribs that Cambrian trilobites possessed the same 

 ability.* Therefore it must have happened very recently in his life 

 history or all traces of the accident would have been removed. But if 

 it happened such a short while ago the chunk must have been removed 

 by a foe more voracious if not actually larger than himself and we are 

 apparently justified in assuming the presence in the Lower Cambrian 

 seas of animals capable of inflicting such an injury. The only other 

 explanation is that he became pinned beneath material dropping from 

 an overhanging ledge, and an apparent crowding and dwarfing of the 

 ribs immediately adjacent to the cut lends a degree of plausibility to 

 the idea that the}- were bruised at the same time. 



So far as we can judge from the present appearance of the edges of 

 the wound it was comparatively clean cut, and made by a jaw capable 

 of cutting not only at the extreme tip but for some distance along each 

 side, for the ribs next in front and back of the one in the middle are 

 cut off diagonally. A Sidneyia-like crustacean (see figure 2) could 

 hardly be expected to clip so symmetrical and clean a section. If we 

 were to hazard a gue>- we would say that the most reasonable conclu- 

 sion would be that it was the work of a fish. These, the earliest known 

 vertebrates, are not known from rocks earlier than those of the imme- 

 diately overlying system, the Ordovician, but ancient, rocks are growing 

 daily more responsive and such a guess is far within the range of 

 probability. 



PROGRAMME OF WINTER LECTURES, 191 7-19 IS. 



December 18, 1917 "Two Years in N. E. Greenland.*' Mr. Frits 

 Johansen, Naturalist on the "Danmark" Expedition, 1906-1908. 



January 8, 1918 "Mobilizing the Forests for War and Peace." Mr. 

 Robson Black, Secretary of the Canadian Forestrv Association. 



January 22, 1918 "Diseases of Domestic Animals.*' Dr. S. Hadwen, 

 Pathologist, Dept. of Agriculture, Ottawa. 



February 5, 1918 "Local Snakes, Frogs and Salamanders: Their 

 Relation to Agriculture." Mr. Clyde L. Patch, Victoria Memor- 

 ial Museum, Ottawa. 



February 19, 1918- "Fishing and the Canadian Fisheries, with 

 Special Reference to the Atlantic Coast." Mr. W. A Found, 

 Superintendent of Fisheries, Ottawa. 



March 5, 1918 "The Fur Seals." Mr. James M. Macoun, C.M.G., 

 Victoria Memorial Museum, Ottawa. 



March 19, 1918 "Naturalists and Tropical Diseases." Major J. L. 

 Todd, Ottawa, lately Professor of Parasitology, McGill Univer- 

 sity. At the conclusion of this lecture the ANNUAL MEETING 

 of the Club will be held. 



*Perhaps the quickness of this recovery in these early forms is the reason 

 for the perfection of the forms which have hitherto been discovered. 



