2^0 



NA TURE 



[7a;i. 25, .877 



and divided with that or more difference in level between 

 the segments, which also shows extreme rapidity of depo- 

 sition ; and although we have proof that we in some cases 

 see the actual soil in which some of the smaller plants 

 orew, still penetrated by their roots, there is no evidence 

 of its having been long occupied, or that it indicates more 

 than a rapid fern growth between recurring floods. We 

 have further, in the fine state of preservation of some of 

 the leaves, which have been doubtless buried before decay 

 set in, and in the breaking up and redeposition of beds, 

 evidence of rapid accumulation ; yet we must not hastily 

 conclude that the time required for the formation of these 

 deposits was, even geologically speaking, short. We over 

 and over again see beds, one above another, which have 

 been cut through and carried away after they had become 

 consolidated, that is, after the muds had become so hard 

 that they have resisted the dissolving power of water and 

 been roiled and redeposited as pebbles and boulders. 



The same spots may have been again and again silted 

 up and denuded before the beds finally remaining were 

 covered up, the same material has been rearranged by 

 different currents perhaps a great number of times, whilst 

 the constant unconformability of the strata may indicate 

 periods of rest or great lapses of time. All our facts as 

 to the depressioa of areas tend to show that it is an ex- 

 tremely slow and imperceptible prccess — slower still when 

 the gener-il depression is intermittent. We have further a 

 totally different kind of evidence, which to my mind is 

 still stronger, of the vast ages that rolled away during the 

 deposhion of these beds. This is the significant fact that 

 the entire marine fauna was completely changed. By 

 mis 1 mean that we have in the London clay a fauna that 

 migrated away, a fauna familiar to us and characterised 

 by great nautili and other shells, Crustacea, &c., peculiar 

 to It. In the succeeding Bracklesham beds we have 

 another totally distinct fauna, so that the duration of the 

 land period was sufficiently long for the fauna of the 

 London clay sea to be entirely changed before the return 

 of the sea whose fauna we have recorded in the Brackle- 

 sham beds. In the Barton beds which overlie the Bourne- 

 mouth deposits, we have again an extensive fauna, most 

 distinctly characterised and widely separated from that 

 of either of the preceding beds just mentioned. 



In many cases it is recognised that variations in fauna 

 are dependent upon the depth of the sea, but such cannot 

 be the case in this instance since we get species belonging 

 to the same genera, so closely resembling each other, that 

 we cannot but infer that they lived under similar condi- 

 tions. And when we come to see, as we do, that this 

 applies to all the -groups, the inference, drawn from one 

 individual group accumulates to an evidence which pre- 

 sents itstlf as at any rate approaching certainty. The 

 well known case of the difference in the fauna of the Red 

 bea and the Mediterranean, which are separated by so 

 narrow a strip of land, has been often referred to as a 

 possible explanation of how different fossil faunas occurring 

 close together may have existed contemporaneously, and 

 do not imply any lapse of time during which changes of 

 climate cccurred; but although in many cases it is impos- 

 sible when a purely hypothetical theory is brought forward 

 to bring an argument to disprove ir, yet in this case there 

 is no evidence whatever in its favour, and what little evi- 

 dence there is bearing on the question, is directly opposed 

 to it ; therefore the other seems the more reasonable ex- 

 planation. The great changes in the flora which I shall 

 mention to you, although principally due perhaps to the 

 great change of level of which we have other indications, 

 may also indicate long lapse of time, l<)ng enough as 1 

 have said for the marine fauna of Bracklesham to develop, 

 to disappear, and to give place to that of Barton, 



These deposits, which have been neglected by geologists, 

 are of extreme importance as being one of the few records 

 \\ e have of land surface. The rocks in which organic 

 remains are lound are aqueous rocks, principally marine ; 



the remains of aquatic animals are more numerous than are 

 those of terrestrial animals, and are, for the same reason, 

 far more numerous than those of plants. Such facts as 

 these give great interest to series of land remains of so 

 complete a nature. We can form an idea of how incom- 

 plete our terrestrial records are when we consider that 

 whilst upwards of 4,4CO plants are growing in Great 

 Bri ain, about 700 only are known fossil, whilst 513 

 testaceous mollusca now inhabit Great Britain, and 4,590 

 were known fossil as far back as 1862. 



The Bournemouth flora seems to consist principally of 

 trees or hard-wooded shrubs, comparatively few remains 

 of the herbaceous vegetation being preserved. 



Parasitic fungi are abundant. Ferns, extremely rare in 

 the lower part of the series, become abundant, as far as 

 the remains go, almost to the exclusion of other vege- 

 tation, towards the close of the middle period. The pre- 

 vailing group seems that of Acrostichum, of which several 

 species are present. We can also determine, with almost 

 certainty, the presence of Angiopteris, Anemia, Nephro- 

 dium, Gleichenia, Lygodium, and there are, besides these, 

 several undetermined forms. 



Of Conifers we have Cupressus and Taxodium, deter- 

 mined by De la Harpe, with the addition of Dacridium 

 and indications of Pinus ; Cycads have disappeared. 



Of Monocotyledons we have indications of reeds and 

 rushes ; Pandanus is represented by its fruit, Nipa- 

 dites ; palms are very abundant, especially in the lower- 

 most beds of Corle, the middle beds of Studland, 

 and the upper middle beds of Bournemouth. Masso- 

 longho has determined Chamoecyparites, in addition 

 to which many fan and feather palms exist, belonging to 

 Flabellaria, Sabal, Phoenicites, and a genus new to the 

 Eocene, Iriartea. A gigantic aroid is also very abun- 

 dant, and the Smilaceae occur in all the fossiUferous beds 

 throughout, and are represented by five or six species. 



The Dicotyledons are, however, most abundant, and it 

 is probable that a vast number of species will be deter- 

 mined from these beds. De la Harpe's list included in 

 1856 :— 



ApetalcB. — Populu?, Ulmus, Laurus, Quercus, and Arto- 

 carpidium, to which Massolongho added Daphnogene. 

 To these we may now add Carpinus, Fagus, Castanea, 

 Salix, Platanus, Ficus, Celtis, numerous Proteaceae, Cin- 

 namomum. 



PoIypetalcE. — Elaeodendron, Rhamnus, Prunus, Juglans, 

 Cluytia, have been already noticed by De la Harpe. We 

 will add, fide Massolongho^ Ceratopetalum, and as new 

 to the Bournemouth flora, Acer, Dodonaea, Celastrus, 

 Eucalyptus, and a number of Leguminosae. 



Monopetalce. — De la Harpe has determined Diospyros ; 

 to this may perhaps be added Porana. 



Cactus and Stenocarpus have been previously men- 

 tioned, and have never previously been found fossil. 



In addition to these we have probably represented 

 almost every genus described from continental Eocene 

 floras, but it is premature, for the reasons already stated, 

 to go further into this question at present. The forms I 

 have mentioned will, however, give you a general idea 0^ 

 the composition of the flora. 



It will have been gathered from the anniversat 

 addresses of our president, Mr. Carruthers, that th<! 

 remains of plants are, if possible, of more interest an^ 

 importance than those of marine animals, as whilst 

 have tlready some idea of the succession and develof 

 ment of animal life, especially of the more purely marine' 

 orders of Crustacea, mollusca, echinodermata, &c., we 

 know very little of the history and development of plant life. 

 Mr. Carruthers laid stress on the somewhat sudden oc- 

 currence of dicotyledons as being unfavourable to the 

 hypothesis of evolution in descent. I concur with him 

 fully that it is difficult to realise that the absence of dico- 

 tyledons can be due to any cause but their absence from 

 the then existing vegetation, yet there are certain causes 



