256 Canadian Record of Science. 



to have separated the Welsh-Scandinavian fauna from the 

 Cambrian faunas of the south of Europe. 



Such land bridges and barriers, no doubt, had an import- 

 ant influence in assisting or retarding the diffusion of lit- 

 toral species in former times, as they have at the present 

 day, but in connection with their influence, it may be 

 well to consider what effect ocean currents of different tem- 

 peratures may have had on the dispersion of marine forms in 

 the Cambrian age. 



Marcou is one of the geologists who still upholds the com- 

 paratively recent origin of the Olenellus fauna, making it 

 more recent than the Paradoxides fauna ; but then he separ- 

 ates from Olenellus the Olenelloid forms found in Sweden 

 and Russia, considering them to be of a more ancient type, 

 and anterior to the Paradoxides genus. 



On the other hand, we find Mr. C. D. WaJcott, since his 

 visit to Newfoundland, expressing the opinion that the 

 Olenellus fauna is anterior to the Paradoxides fauna. This 

 is on the assumption that all the Olenelloid forms are of 

 nearly the same age, and anterior to the Paradoxidean 

 forms. In this view he has the support of many European 

 palaeontologists, and especially of specialists in the Cambrian 

 and Ordovician faunas. 



Between these two extremes are several palaeontologists, 

 chiefly in America, who are not prepared yet to accept the 

 view that the Olenelloid forms are always and everywhere 

 older than the Paradoxidean. The actual infra-position has 

 been shown, so far as America is concerned, only in New- 

 foundland. 



In Acadia, though the remains of Olenellus and its allies 

 have not been found, those of other species of animals 

 occur, analogous to forms of the Holmia beds in the north 

 of Europe, and so it may be inferred that genera of the 

 Olenellus group will in time be found here. But the entire 

 priority of all the Olenelloid trilobites to the Paradoxides 

 in every part of the globe, may be considered an open 

 question, or, to say the least, not fully established. 



A review of the Cambrian faunas of Europe and North 



