TRANSACTIONS OF SECTION C. 645 



laTjoratories could scarcely he said to bave existed in this country. Truly may the 

 scieutiHc youth of to-day make the boast — 



H/ieis ixeu narepaiv fxey dixeivuves fi'xofied' civai — 

 ^ We are much better off than our fathers were/ while we, the fathers, have the 

 poor consolation of knowmg- that when they are fathers their children will say the 

 same of them. There is reason to suppose that our science will advance more 

 swiftly in the future than it has in the past, because it has more delicate and 

 precise methods of research than it ever had before, and because its votaries are 

 more numerous than they ever were. 



In 1864 the attention of geologists was mainlv given to the investi^-ations of 

 the later stages of the Tertiary Period. The bent of my pursuits inclines me to 

 revert to this portion of geological inquiry, and to discuss certain points which 

 have arisen during the last few years in connection with the classiHcatory value of 

 iossils, and the mode in which they may be best used for the co-ordination of strata 

 m various pai-ts of the world. 



The principle of homotaxy, first clearly defined bv Professor Huxley, has been 

 lully accepted as a guiding principle in place of synchronism or contemporaneity, 

 and the tact of certain groups of plants and animals succeeding one another in a 

 defamte order, in countries remote from each other, is no longer taken to implv 

 that each was livmg in the various regions at the same time, but rather, unless there 

 be_ evidence to the contrary, that they were not. While, however, there is a 

 universal agreement on this point among geologists, the classificatory value of the 

 various divisions of the vegetable and animal kingdoms is still under discussion 

 and, as has been very well put by my predecessor in this chair at Montreal 

 sometimes the evidence of one class of organic remains points in one direction while 

 the evidence of another class points in another and wholly different direction as 

 to the geological horizon of the same rocks. The Flora, put into the witness-box bv 

 the botanist, says one thing, while the Mollusca or the ^-ertebrata say another 

 thing in the hands of their respective counsel. There seems to be a tacit assump- 

 tion that the various divisions of the organic M-orld present the same amount of 

 variation in the rocks, and that consequently the evidence of every part of it is of 

 equal value. 



It will not be unprofitable to devote a few minutes to this question, premisino- 

 that each case must be decided on its own merits, without prejudice, and that the 

 whole ot the evidence of the flora and fauna must be considered. We will take the 



flora first. 



The cryptogamic flora of the later Primary rocks shows but slight evidence of 

 change. The forests of Britain and of Europe generally, and of North America, were 

 composed practically of the same elements-Sigillaria, Calamites. and conifers allied 

 to the binkho— throughout the whole of the Carboniferous (16,330 feet in thickness 

 in Lancashire and Yorkshire) and Devonian rocks, and do not present greater 

 diflerences than those which are to be seen in the existing forests of France and 

 Cjrermany. _ 1 hey evidently were continuous both in space and time, from their 

 beginning in the Upper Silurian to their decay and ultimate disappearance in the 

 Permian Age. _ This disappearance was probably due to geographicnl and climatic 

 changes following the altered relations of land to sea at the close of the Carboni- 

 ferous Age, by which becondary plants, such as Voltzia and IVaMia, were able to 

 fand their way by migration from an area hitherto isolated. The Devonian forma- 

 tion is mapped off from the Carboniferous, and this from the Permian, but to a 

 slight degree by the flora, and nearly altogether by the fauna. While the fauna 

 exhibits great and important changes, the flora remained on the whole the same. 



Ihe torests of the Secondary Period, consisting of various conifers and cycads. 

 also present slight differences as they are traced upwards through the Triassic and 

 Jurassic rocks, while remarkable and striking changes took place in the fauna, which 

 mark tlie division of the formations into smaller groups. As the evidence stands at 



Prf^%- ,-f ''^'''''^l °t J^"; y^"^ ^^ °°* ^^^^^ ^"^ ^"^y important character from those 

 of the Oolites or the Wealden, and the Salisburia in Yorkshire in the Liassic Age is 

 very similar to that of the Island of Mull in the Early Tertiary, and to that (Salia- 

 tuna adtantifolia) now living in the open air in Kew Gardens 



