Notices of Memoirs — Dr. R. H. Traqumr's Address. 463 



area than the Cambrian, but they also occupied longer time in their 

 formation ; hence the area from which they were derived need not 

 necessarily have been larger than that of the preceding period. 



Great changes in the geography of our area ushered in the Silurian 

 system : its maximum thickness is found over the Lake district, and 

 amounts to 15,000 feet; but in the little island of Gothland, where 

 all the subdivisions of the system, from the Llandovery to the Upper 

 Ludlow, occur in complete sequence, the thickness is only 208 feet. 

 In Gothland, therefore, according to our computation, the rate of 

 accumulation was one foot in 7,211 years. 



With this example we must conclude, merely adding that the same 

 story is told by other systems and other countries, and that, so far as 

 my investigations have extended, I can find no evidence which would 

 suggest an extension of the estimate I have proposed. It is but an 

 estimate, and those who have made acquaintance with ' estimates ' 

 in the practical affairs of life will know how far this kind of 

 computation may guide us to or from the truth. 



III. — The Bearings of Fossil Ichthyology on the Problem of 

 Evolution ; being the Address to the Zoological Section. 

 By Kamsay H. Traquair, M.D., LL.D., F.E.S., President of the 

 Section. (Slightly abridged.) 



I HAVE been told that an idea is prevalent in the minds of recent 

 biologists that the results of Paleeontology are so uncertain, so 

 doubtful, and so imperfect, that they are scarcely worthy of serious 

 attention being paid to them. The best answer I can make to such 

 an opinion, if it really does exist, is to try to place before you some 

 evidence that Palseontology is not mere fossil shell hunting, or the 

 making up of long lists of names to help the geologists to settle 

 their stratigraphical horizons, but may present us with abundance 

 of matter of genuine biological interest. 



Since the days of Darwin, there is one subject which more than 

 all others engrosses the attention of scientific biologists. I mean 

 the question of Evolution, or the Doctrine of Descent. From the 

 nature of things it is clear that the voice of the paljBontologist can 

 only be heard on the morphological aspect of the question, but to 

 many of us, including myself, the morphological argument is so 

 convincing that we believe that even if the Darwinian theory were 

 proved to-morrow to be utterly baseless, the Doctrine of Descent 

 would not be in the slightest degree affected, but would continue to 

 have as firm a hold on our minds as before. 



Now as Palgeontology takes us back, far back, into the life of the 

 past, it might be reasonably expected that it would throw great 

 light on the descent of animals, but the amount of its evidence is 

 necessarily much diminished by two unfortunate circumstances. 

 First, the terrible imperfection of the geological record, a fact so 

 obvious to anyone having any acquaintance with geology that it 

 need not be discussed here ; and secondly, the circumstance that save 

 in very exceptional cases only the hard parts of animals are pre- 

 served, and those too often in an extremely fragmentary and disjointed 



