18G9.] DAWSON — IDEAS OF DERIVATION. 129 



Eocene for the multitude of Ruminants and Carnivores and 

 Quadrumana of the Modern time. 



But it may be said, and truly, that these higher forms of life 

 put the doctrine of derivation to the severest test. If we take 

 marine invertebrata, we may trace analogues of these back into the 

 earliest geological periods, and as the species are very numerous, 

 and their structures more simple, it is easier to imagine a 

 continuous derivation with respect to them. Still, even here such 

 facts as the v:ist multiplication of species of Trilobites, Ammonites, 

 Belemnites, and Ganoid Fishes, at different periods of Geological 

 time, and their disappearance without modified successors, point to 

 limitations of any law of derivation that maybe suggested. 



To sum up where all is so uncertain is not easy ; but we may, 

 I think, affirm that if existing animals are derivative as modified 

 descendants of others — (1) They belong to a vast number of 

 lines of modification which would require to be traced backward 

 separately. (2) That many of these lines end abruptly in com- 

 paratively recent periods, perhaps in consequence of our defective 

 information, perhaps because of some other law of creation. 

 (3) That in some periods a series must suddenly bud forth 

 into many ramifications, and in others contract to a few 

 representations or be altogether dropped. (4) That the beginning 

 of such series may take place in a different manner from 

 derivation, and that the law of new series is probably different 

 from that of those of longer derivation. (5) That it is absurd 

 to suppose that any modern animal has originated from any now 

 contemporary with it (e.g., man from the gorilla or bears from 

 seals), since all these existing species must belong to series to be 

 traced backward through species now extinct, and possibly 

 unknown to us. (6) That while it is obvious that such 

 derivation must be related to contemporary physical changes, our 

 views of the nature of that relation must depend on those which 

 we take of the causes of derivation itself 



Before proceeding farther we may remove another of the 

 " theological" misconceptions under which Owen and some other 

 writers on this subject seem to labour. They think that the 

 " Biblical flood" interposes some difficulties in the way of their 

 speculations as to the origin of species. They may readily be 

 relieved from all embarrassment on this subject. The language 

 of the Noachian record in Genesis implies that the Deluge was 

 universal only in so far as man was concerned. The catalogue of 



