NA TURE 



193 



THURSDAY, JUNE 28, 1883 



THE LINKS OF THE ANIMAL 

 WORLD 

 Les Enchainements du Monde Animal dans les Temps 

 Geologiques. Fossiles Primaires. Par Albert Gaudry, 

 Professeur de Paldontologie au Muse'um d'Histoire 

 Naturelle. (Paris: F. Savy, 1883.) 



IV /T GAUDRY, a distinguished palaeontologist, con- 

 ■*•"■»• tributed five years ago a very interesting volume 

 on the important and much debated question of the 

 mammalia of the Tertiary epoch (see Nature, vol. xviii. 

 P- 537)- The volume which he now publishes relates to 

 the same gua'stio vexata, but takes into consideration 

 only the fossils that are to be found in primary strata. 

 The author's proposed task is the same in both cases ; he 

 undertakes to find the links and connections that may 

 exist between the animals which have successively or 

 simultaneously inhabited the lands and seas of past 

 epochs. 



A great deal has been written on the transformism-theory 

 of Lamarck and Darwin, and it must be expected that 

 much more will be written. One of the principal objec- 

 tions made to it is that if man is really the descendant of 

 the ape, and the ape that of other mammalia, if, generally, 

 there exist links between all animals, living and extinct, 

 so that all animals trace their origin to a common 

 ancestor, how is it that no link really exists between man 

 and ape, or between fish and frog, or between vertebrate 

 and invertebrate? Embryological considerations, it is 

 said, show a real connection between very different 

 animals : a frog for instance is a fish for some time during 

 its youth, and amphioxus looks very much like an 

 ascidian. 



But, notwithstanding numerous arguments to support 

 Lamarck's theory, no transformist can show any species 

 gradually losing its peculiar characters to acquire new 

 ones belonging to another species, and thus transforming 

 itself. However similar the dog may be to the wolf, no 

 one has found any dead nor living animal or skeleton 

 which might as well be ascribed to wolf as to dog, and 

 therefore be considered as being the link between the 

 two. One may say exactly as much concerning the ex- 

 tinct species ; there is no gradual and imperceptible 

 passage from one to another. Moreover, the first animals 

 that lived on this earth are not, by any means, those that 

 one may consider as inferior and degraded. 



M. Gaudry in the first pages of his work states very 

 clearly that he prefers the theory according to which links 

 do exist between the extinct animals of different groups, 

 but he does not show that facts support it yet very 

 strongly. 



The opinion one may entertain as to this question 

 being entirely dependent upon facts and the manner of 

 understanding them, let us now turn over the leaves of 

 M. Gaudry's book and see whether we can find in it some 

 firm support to Lamarck's and Darwin's theories. 



According to J. Barrande's numerations the number of 

 the species contained in the Silurian strata, comprising 

 the Cambrian, is the following : — 

 Vol. xxviii. — No. 713 



Sponges and Protozoa 



Corals 



Echinodermata 



Worms 



Trilobites 



Other Crustaceans ... 



Bryozoans ... 



Urachiopods 



Lamellibranchs 



Heteropods and Pteropods 



Gastropods... 



Cephalopods 



Fishes 



Of uncertain relations 



Species. 



'53 



7i8 



588 



185 



1579 



348 



478 



1567 



1086 



39o 



i3'6 



1622 



40 



4 



10,074 

 Thus, in the first of the primary strata nearly all the in- 

 vertebrates are to be found— excepting insects— and the 

 first vertebrate animals appear. 



Generally speaking, and leaving Eozoon canadense and 

 Archaospharina out of the question, worms are the 

 oldest fossils to be found in the Silurian strata. It is so 

 in England (Caerfay), in Scandinavia, in France, in 

 Bohemia (Przibram), in America (St. John). In Russia, 

 Crustaceans (Obolus) are the first fossils found. It must 

 be therefore acknowledged that life has not begun on 

 earth with the lowest forms. M. Gaudry, it must also be 

 said, does not believe that such has been the case. M. 

 Gaudry's principal aim is to show that, for instance, all 

 Polyzoa somewhat resemble each other, and that the 

 species are so very similar that the links between them are 

 evident ; but he does not pretend to show the relations 

 between Worms and Crustaceans for instance, and try to 

 find links between them. 



M. Gaudry shows easily enough that, according to 

 Nicholson's, Verril's, and Moseley's views, the arrange- 

 ment and classification of Polyp corals, Zoantharia, 

 Tubipora, Tabulata, and Rugosa is a very difficult thing 

 inasmuch as by some points of their anatomy the 

 species under consideration should come in one group 

 and by others come in another group. The same thing 

 may be said of Echinoderms. 



Between Starfishes and Crinoids there are many links ; 

 others exist between Sea-urchins and Starfish, and Holo- 

 thurians. As concerns Brachiopods, M. Gaudry remarks 

 that the oldest species of animal on earth is the Lingula, 

 so abundantly found in the Lingula Flags of the English 

 Silurian. It exists to this day, being the best example of 

 " fine old age" yet recorded. Links between the various 

 genera of Brachiopods are not yet very firmly established. 

 Mr. Davidson is opposed to the idea, but Mr. N. Glass's 

 (of Manchester) researches give on the contrary some 

 support to it, by showing how much the arms of the 

 Brachiopods vary and differ in different animals of the 

 same species. Mr. Davidson says that it is often very 

 difficult to ascertain exactly the species of the individuals. 

 Though not having seen, generally speaking, a great 

 number of individuals of the same species, I may say 

 however that of about twenty Attypa reticularis often 

 seen and handled by myself in one of the Parisian geo- 

 logical collections, not two were strictly alike. I have no 

 doubt that the same is true of all, or at least most, 

 species. 



K 



