286 THE CANADIAN NATURALIST. [Yol. vii. 



«on the general law that in times of continental elevation newer 

 productions of the land are mixed with more antique inhabitants 

 of the sea ; while on the contrary in times of subsidence older 

 land creatures are liable to be mixed with newer products of the 

 sea. Thus in Vancouver's Island plants which Heer at first 

 regarded as Miocene have been washed down into waters in 

 which Cretaceous shell-fishes still swarmed. Thus Cope main- 

 tains that the lignite -bearing or Fort Union group contains 

 remains of cretaceous reptiles, while to the fossil botanist its 

 plants appear to be unquestionably Tertiary. Hence also we 

 are told that the skeleton of a Cretaceous Dinosaur has been 

 found stuffed with leaves which Lesquereux regards as Eocene. 

 At first these apparent anachronisms seem puzzling, and they 

 interfere much with arbitrary classifications. Still they are 

 perfectly natural, and to be expected where a true geological 

 transition occurs. They afford, moreover, an opportunity of 

 settling the question whether the introduction of living things 

 is a slow and gradual evolution of new types by descent with 

 modification, or whether, according to the law so ably illustrated 

 by Barrande in the case of the Cephalopods and Trilobites, new 

 forms are introduced abundantly and in perfection at once. 

 The physical change was apparently of the most gradual char- 

 acter. Was it so with the organic change. That it was not is 

 tipparent from the fact that both Dr. Asa Gray and Mr. Cope, 

 who try to press this transition into the service of evolution, are 

 •obliged in the last resort to admit that the new flora and fauna 

 must have migrated into the region from some other place. 

 Oray seems to think that the plants came from the north, Cope 

 supposes the mammals came from the south; but whether they 

 were landed from one of Sir William Thomson's meteors, or 

 produced in some as yet unknown region of the earth, they 

 cannot inform us. Neither seems to consider that if giant Se- 

 quoias and Dicotyledonous trees and large herbaceous mammalia 

 arose in the Cretaceous or early Tertiary, and have continued 

 substantially unimproved ever since, they must have existed 

 somewhere for periods far greater than that which intervenes be- 

 tween the Cretaceous and the present time, in order to give 

 them time to be evolved from inferior types ; and that we thus 

 only push back the difficulty of their origin, with the additional 

 disadvantage of having to admit a most portentous and fatal 

 imperfection in our geological record. 



