Section IV., 1892. [ 3 ] Trans. Roy. Soc. Canada. 



I. — On tli.r Diffusion <uid Sequence of the Cambrian Faunas — President I'll Address 



for the Year. 



By G. F. Matthew, M.A. 



Introductory— 1. Graptoliles as deep-water organisms — 2. Other deep-water organisms -3. Physical conditions 

 iifTecting distribution — 4. Opinions of Marcou and Walcott — 5. Contrasted genera, Olenellus- 

 Haradoxides — 6. Dicelloceplialus-Dictyonema — 7. MacUirea-Tetragraptus — 8. Orthoceras- 

 Dicranograptus — 'J. Tabular view of migrations. 



It is with some hesitatiou that I have choseu as the subject of this address a topic 

 related to my studies of past years ou the fauuas of the St. Johu G-roup. My apology for 

 doiuft- this, and for uot taking a subject of more general interest is, that I wish to give 

 completeness to my work on these fauuas by glancing further afield, and noting the light 

 which it throws on certain phenomena of the life of the Cambrian age in North America 

 generally, and in Europe. 



Since this Society was instituted and my first paper ou these faunas was read, great 

 additions have been made to our knowledge of the Cambrian system and its faunas. The 

 wide areas of Cambrian rocks in Sweden and Norway have been assiduously examiiied by 

 a talented band of naturalists includiug Brogger, Tullberg, Nathorst and Holm. Dr. 

 Schmidt, in Russia, has worked up some important discoveries in that (country, Menighini 

 has studied the fossils found iu Sardinia, and Messrs. Barrois and Bergeron by their ex- 

 plorations in Spain and the south of France have added greatly to our knowledge of the 

 Cambrian faunas of that region. 



Our kinsmen iu Great Britain have not been idle, and notably Hicks, Lapworth and 

 Peach have made important additions to the Cambrian faunas of the mother-land. Of late 

 years on this side of the Atlantic the work begun by E. Emmons and James Hall has 

 been carried on chiefly by Ford, Whitfield and Walcott, and especially of late by the latter, 

 who owing to his position as a palœoutologist of the United States Geological Survey has 

 been able to devote much time to the exploration and study of the Cambrian rocks. 



Through the labours of these men our knowledge of Cambrian geology has been 

 greatly extended, and we are now able to make comparisons between the Cambrian rocks 

 and faiinas of dirterent countries with far greater exactness than was possible ten years 

 ago. 



In opening this address I should preface it with the remark that the conclusions 

 drawn are largely based on negative evidence. This is unavoidable since the geological 

 record is imperfect, and iu the futiire it may be necessary to modify these conclusions to 

 some extent, if facts of an opposing nature are presented. The address is intended as an 

 expression of our present knowledge. 



I. — The Graptolites as Deep-water Organisms. 



In speculating upon the influences which have caused changes in the population of 

 the seas at a period so remote as the Cambrian age, we can only with much hesitatiou 



