TRANSACTIONS OF THE SECTIONS. 99 



large outstanding amount of fact incapable of being thus explained away ; the problem 

 demands some other solution. Suppose it true that in some cases the organic dissi- 

 milarity, which has been described, was due to differences in the mineral character of 

 the ancient sea-bottoms; still when we have two areas like Lower South and North 

 Devon, consisting of contemporary, almost contiguous, and scarcely dissimilar depo- 

 sits, one rich and the other poor in the variety of its organic remains, having together 

 233 species yet no more than 8 in common, some other solutionis obviously needed. 



Was there a terrestrial barrier separating the two areas ? Was that which is now 

 Central Devon occupied by dry land, which stretched far both east and west, while 

 the waves of the Devonian ocean rolled over the north and south of the county? All 

 the known physical facts are opposed to such a hypothesis. Moreover, 8 species 

 actually did migrate from one area to the other; eight proofs, then, that a passage did 

 exist, unless we suppose that both areas were peopled from some more distant centre 

 or centres of dispersion. 



It may be asked, were not these eight the remnants of an earlier (a Silurian) fauna? 

 forms of life whose localization had been determined by an earlier distribution of land 

 and water? Eight Silurian forms do make their appearance amongst the Devonians 

 of Devon and Cornwall ; are not these the very eight thus common ? Now it so hap- 

 pens that they are not ; in fact there is not a single Silurian form in the Lower North 

 Devon series. This hypothesis then fails. Shall we hold with Professor Phillips, that 

 " this unequal diffusion of definite forms of life may often be ascribed to oceanic cur- 

 rents*?" 1 cannot but think that fewer difficulties attach to this than to any other 

 hypothesis which has been proposed. It simply requires us to suppose that a per- 

 sistent oceanic stream, flowing through Central Devon, separated the contemporary 

 deposits of the north and south, and formed, by its thermal or other qualities, an all 

 but impenetrable barrier to the marine tribes. 



Though, as we have seen, at least so far as Devonshire is concerned, the basis 

 entirely fails on which scepticism respecting the existence of a Devonian period has 

 been founded, namely, that ' : the blending of Silurian and Carboniferous corals is of 

 common occurrence," yet if the word "fossil" be substituted for "coral," a blending 

 of this kind certainly does occur, and doubtless the fact is not without a meaning. 

 Eight species from the older and 58 found in the more modern (a total of 66) meet 

 in Devon. Are they necessarily so many proofs that the rocks in which they were 

 inhumed are not Devonian? It must be borne in mind that there are 281 species 

 that are neither Silurian nor Carboniferous, but of an intermediate character. The 

 palceontological argument then stands thus : there are 66 witnesses supposed to 

 testify that the rocks are not Devonian, and 281 (upwards of 4 to 1) emphatically 

 declare that they are. But the adverse witnesses are by no means agreed amongst 

 themselves ; eight of them claim the rocks as Silurian, and fifty-eight as Carboniferous. 

 Is there no way of interpreting their evidence, but that of sacrificing the Devonian 

 system altogether? Are they not so many arguments in favour of the gradual pas- 

 sage of system into system ? so many difficulties in the way of a belief in catastrophes? 

 by which I mean convulsions (or call it by any other name) which, from time to 

 time, shook the very life out of the world, causing a series of universal and synchro- 

 nous depopulations of our planet. May we not regard them as so many tints inter- 

 mediate, both in quality and in place, between the extreme bands of the rainbow, 

 uniting them into one beautifully graduated chromatic spectrum, so softly blending 

 as to render it impossible to define the exact place of lines of demarcation? which 

 perhaps have not, and never would have been supposed to have, a physical existence, 

 had not observers hastily generalized from the imperfect evidence obtained during 

 a period of colour blindness. 



But if the Devonshire rocks were handed over to the Carboniferous system, we 

 should not be quit of the doctrine that some of the forms of one period have, at least 

 in some instances, lived through it into the next; for the opponents of a Devonian 

 period not only admit this, but rest their case on the alleged fact that " Silurian and 

 Carboniferous forms are found blended together in Devonshire and elsewhere." When, 

 nearly a quarter of a century ago, Mr. Lonsdale first suggested that the fossils of 

 South Devon, taken as a whole, exhibited a peculiar character intermediate to those 

 of the Silurian and Carboniferous groups, he was perfectly aware that amongst them 



* Quarterly Journ. Geol. Soc. vol. xvi. p. xl. 



7* 



