Feb. 23, 1888] 



NATURE 



403 



cellanous types ot the Foraininifera from itie Pala;;uzoic rocks m ly 

 he due, not to their non-existence when those rocks were formed, 

 but to the fact of their shells being composed of the unstable 

 aragonite. 



Such facts as these must convince any unprejudiced parson of 

 the absolute necessity, to the naturalist who attempts to study 

 •extinct forms, of an acquaintance with the nature of the mineral 

 •changes which organic remains undergo. In his interesting 

 memoir upon those curious and enigmatical fossils, the Recepta- 

 culitida:, Dr. Hinde has admirably shown the advantages of this 

 combination of biological and petrographical study. 



In this connection I cannot avoid alluding to a very prevalent 

 and, as I cannot help thinking, very erroneous notion, that an 

 intermingled zoological and palaeontological collection, however 

 inconvenient, would certainly be very instructive. To this view 

 I offer the strongest protest, for 1 believe that the mistakes 

 which would arise from the examination of such a collection 

 would far outweigh any instruction to be derived from it. 



I fail to see what useful lesson would be taught by swamping 

 a collection of the lizirds, snakes, tortoises, and crocodiles living 

 at the present day with the vast slabs containing the relics of 

 Keptilia which have existed in periods ranging from the Permian 

 10 the Pliocene. Nor is it apparent to me why the precious 

 remains of Arclueopteryx should be hidden away among a wilder- 

 ness of bird-skins. 



Any arrangement which could lead to the idea that even the 

 richest collection of fossils is in any way commensurable with 

 ihe assemblages of specimens that in our museums represent the 

 ■existing fauna is very greatly to be deprecated. So numerous 

 are the gaps among fossil faunas, owing to the fact that only 

 animals with hard parts, and, as a rule, only those that lived in 

 the sea, had any chance of preservation, that the finest pala;onto- 

 4ogical collections are, and must always remain, extremely frag- 

 mentary. We have, in the past, fallen into so many and such 

 /grievous eiTors, by ignoring the imperfection of the geological 

 record, that we may well hesitate before doing anything that 

 ■would confirm this mischievous delusion. 



On the other hand, it may be pointed out that our acquaint- 

 ance with extinct forms of life has increased to such an extent in 

 •recent years that a biologist may well be pardoned for not 

 aealizing the vastness and importance of the problems involved 

 in the study of fossils. It can only be a very inadequate idea of 

 the value of palaeontological evidence which leads fossils to be 

 'garded (like the fauna and flora of a newly-discovered territory) 

 i; simply supplying a few missing links required to fill up gaps 

 in a natural-history classification, or as the appropriate ballast 

 /or a Noah's Ark on a scale of national grandeur. Small as may 

 l)e the whole bulk of a palfeontological collection in the eye of 

 the student of recent forms, its great and transcendent value 

 depends on the fact that the objects composing it belong to the 

 /faun IS and floras of periods widely separated from the present 

 and from one another. The discovery of a new type of reptiles 

 in the Trias is a very different matter from the detection of an 

 equally remarkable form living in New Zealand. The latter 

 may, it is true, be a singular survival of some old type ; but the 

 former is an actual landmark in the course of reptiHan develop- 

 ment ; and by the study of the fossil we are actually brought 

 much nearer to the solution of the problems connected with the 

 history of that development than is possible by the study of any 

 recent form. 



In pointing out how vast has been the progress of our know- 

 ledge in recent years concerning the ancient life of the globe, I 

 may remind you of the estimates made by Prof. Huxley when 

 speaking from this chair a little more than a quarter of a century 

 ago. He then characterized " the positive change in passing 

 from the recent to the ancient animal world" as "singularly 

 small " ; and he regarded the extinct orders of animals as not 

 amounting "on the most liberal estimate" to more than one- 

 •tenth of the whole number known. The evidence which has 

 been accumulated during the last twenty-five years, however, 

 lias modified this estimate in a remarkable manner, as no one 

 would be more ready to admit than the author of it himself. 



There is no little difficulty in making a calculation of the pro- 

 portion of living to extinct orders, owing to the discrepancies in 

 the opinions of zoologists and comparative anatomists as to what 

 are the characters which ought to be considered as of ordinal 

 rank. For my present purpose I very gladly avail myself of the 

 useful " Synopsis of the Animal Kingdom " prepared by Mr. E. 

 T. Newton, which is "founded on the classification proposed by 

 Prof. Huxley, with such modifications as are rendered necessary 

 by recent discoveries." 



We may, I think, take the whole number of living orders of 

 animals generally accepted by zoologists at about 108. But in 

 any comparison of these with fossil forms, it is only fair 10 

 exclude from our consideration such as possess no hard parts 

 and stand little or no chance of being preserved in a fossil state. 

 Few would be bold enough to doubt that such soft-bodied forms 

 must have existed in the past, or that they probably bore about 

 the same proportion to the forms with hard skeletons as in the 

 existing fauna ; even the boldest sceptic on this subject would, 

 I should think, be convinced by such singular accidents as that 

 of the finding of the impre-ision of Khizosto miles, one of the 

 Discophoroe, preserved in the soft calcareous mud of the Solen- 

 hofen Slate. 



Now among the 108 living orders of animals, at least 36 

 are totally destitute of any hard parts capable of being preserved 

 in a fossil state, and we have thus left 72 living orders with 

 which our comparison of the extinct orders must be made. 



What is the number of orders which must be created to receive 

 extinct forms, is a question that has given rise to wide diversities 

 of opinion in recent years. While few naturalists would c )n- 

 sider 18 as an excessive estimate, there are others who would 

 probably double that number. 



Taking the lower estimate and comparing the 18 extinct 

 orders with the 72 living ones which contain animals with hard 

 parts, we find the proportion of extinct orders to be 20 per cent, 

 of the whole number known at the present time. 



But in comparisons of this kind, it must be remembered that 

 there is an unconscious tendency among the students of recent 

 forms of life to under-cstimate the differences between extinct and 

 living forms. If we take such groups as the Graptolitida, the 

 MontictiliporidcE, and the Slroinatoporida, of the nature of the 

 polyps of which we can know nothing, we can only place them 

 in existing orders on the ground of some very general analogies 

 in the skeleton. How little this may be worth, recent zoological 

 researches, like those of Prof. Moseley on the Milleporida and 

 the StylasteridcE have amply shown. 



The students of existing forms of life have arranged their 

 pigeon-holes ; and into those pigeon-holes our unfortunate fossils 

 are too often made to go. If there were no other objection to 

 the wholesale commingling of recent and fossil types in a 

 museum, there would be the valid and insuperable one arising 

 from the fact that there are very considerable and important 

 groups of fossils which cannot, without violence, be made to find 

 any place in our accepted classification of existing animals— and 

 perhaps never will. 



If, however, we consider the modifications which have been 

 brought about in our views concerning the relations of extinct 

 to living forms by the important discoveries that have been made 

 since 1862, we shall be impressed by the conviction that no com- 

 parison of the numbers of living and extinct orders can give any 

 adequate idea of the important influence of palaeontological 

 studies upon biological thought. The discovery of transitorial 

 forms, like the Archaopteryx, the toothed birds of America, and 

 the leptiles with avian affinities, together with the working out 

 of the rich faunas of the Rocky Mountains, of Pikermi, Quercy, 

 and the Siwaliks, of the Pampean formations of South America, 

 the Karoo beds of South Africa, and the caves of Australia, have 

 already done much towards revolutionizing the ideas held 

 twenty-five years ago by biologists concerning the significance 

 and value of fossil forms. While the recognition of the 

 less specialized precursors of such types as the horse and the 

 elephant have perhaps produced most effect in removing 

 objections to evolutionary doctrines, the light thrown by the 

 stlxdy of fossil forms on the manner in which individual structures 

 have arisen, as has been so well shown by Prof. Alexander Agassiz, 

 in the case of the Echinodermata, opens up to us a wide and 

 perhaps far more hopeful field of inquiry. Wft are, however, 

 only at the beginning of the great task of utilizing the grand 

 palaeontological collections of mammals, of reptiles, of fishes, 

 and of the various groups of the invertebrates, for explaining 

 the significance and tracing the origin of the structures found in 

 living types. 



While maintaining that studies of this kind demand and justify 

 the concentration of the labours of a special class of investigators, 

 I feel sure that no one will misinterpret my meaning as to the 

 qualifications required by the students of fossil forms. Far from 

 suggesting that the palaeontologist may be one destitute of a 

 proper biological training, or that he may be satisfied with an 

 equipment of knowledge which would be insufficient for a 

 systematic zoologist or botanist, I would maintain thit no one 



