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nearly a century since, that strata may be identified by organic 

 remains. Most of the species of the latter prevalent in one 

 formation are peculiar to it, whilst some survive through two 

 or more of the successive stages of the solid deposits of the 

 earth ; new forms come in at every stage ; and, until some 

 competent second cause can be established accounting for these 

 new appearances, we must perforce call them creations. The 

 similarity of the new forms to the old, and the harmony of the 

 whole, oblige us to term it creation bj law, — a law very 

 similar to evolution, for the forms succeed each other with 

 differences so slight, that, but for the permanency of the 

 effects, they might be frequently assigned to casual variation. 

 But the results appear to show that every step requires and 

 displays some fresh adjustment, the exercise of a mind ah extra. 

 What differences in organic life may be classed as mere modi- 

 fications, and what may be deemed new departures, must be 

 the subject of protracted observation, and perhaps of dispute, 

 but the distinction is not the less real for this. The researches 

 of Mr. Darwin, though not successful in piercing the mystery 

 of the modus operandi, have yet taught us much concerning 

 the limits of variability. They certainly have not established 

 the fact of unlimited variability, which would be requisite for 

 the maintenance of the theory of evolution. 



Reverting to the main scope of the present argument, I 

 have to state that, so far as we know, the cyrtoceras and the 

 orthoceras were the first creatures of their class. Previously 

 to their appearance, the rocks show the presence of molluscs 

 of entirely different and lower type. It is not pretended that 

 amongst the latter any ancestor of the cephalopods can be 

 detected. It is certain, says the accomplished Monsieur 

 Gaudry, that the extinct kinds had no influence whatever in 

 the formation of their successors. In palasontology evolution 

 subsists only as a mental conception ; as we have seen, the two 

 leading forms which are selected by the Rede lecturer, were 

 present at the earliest life-period of which we have any trace 

 of anything at all like them. 



Of course, the differences in the form of the shell are simply 

 indicative of differences in the contained animal. We have 

 no difiiculty in concluding that a constant transmissible dif- 

 ference in the form or curvature of the shell is the result of 

 a similarly constant difference in the living animal. 



One internal difference between cyrtoceras and orthoceras 

 is in the usual position of the siphuncle, the tube which runs 

 from the body of the animal backward through the chambers. 

 In orthoceras, though not absolutely invariable, yet it is very 

 nearly so, so much so as to be considered characteristic, 



