Forbes drew attention to a certain community amongst birds and other vertebrates, invertebrates, and amongst plants, on all the lands stretching towards the south pole.
As regards invertebrates, very few species or genera are peculiar to Liberia so far as is yet known, though there are probably one or two butterflies of local range.
Heider, Handbook of the Comparative Embryology of Invertebrates (trans.
Sci., 1901.) the only two invertebrates which had impressed the minds of early men sufficiently to be raised to the dignity of astronomical representation.
Fossils of both vertebrates and invertebrates are also common in the Permian and Jurassic formations.
Birds and mammals take the first place; the leading collections devote a good deal of attention to reptiles and batrachians; fishes and aquatic invertebrata are most often to be found only when there are special aquaria, whilst non-aquatic invertebrates are seldom to be seen and at most consist of a few moths and butterflies, spiders, scorpions and centipedes, molluscs and crustaceans.
His speculations on phylogeny, or the descent of invertebrates and vertebrates, were, however, most fantastic and bore no relation to palaeontological evidence.
This was due to the much greater completeness and abundance of material afforded among invertebrate fossils, and it was manifested in the demonstration of two great principles or laws: first, the law of recapitulation, which is found in its most ideal expression in the shells of invertebrates; second, in the law of direct genetic succession through very gradual modification.
Thus the recapitulation law, which had been built up independently from the observations and speculations on vertebrates by Lorenz Ofen (1779-1851), Johann Friedrich Meckel (1781-1833), St Hilaire, Karl Ernst von Baer (1;92-1876) and others, and had been applied (1842-1843) by Karl Vogt (1817-1895) and Agassiz, in their respective fields of observation, to comparison of individual stages with the adults of the same group in preceding geological periods, furnished the key to the determination of the ancestry of the invertebrates generally.
He was the first to attempt a comprehensive treatment of all invertebrates from the genetic point of view; but unfortunately his great work, entitled Die Stcimme des Thierreichs (Vienna and Prague, 1889), was uncompleted.
The most striking feature of exploration for invertebrates, next to the world-wide extent to which exploration has been carried on and results applied, is the early appearance of life.
Among invertebrates Barrande's doctrine of centres of origin was applied by Hyatt to the genesis of the Arietidae (1889); after studying thousands of individuals from the principal deposits of Europe he decided that the cradles of the various branches of this family were the basins of the CSte d'Or and southern Germany.
Independent evolution of parts is well shown among invertebrates, where the shell of an ammonite, for example, may change markedly in form without a corresponding change in suture, or vice versa.
Many examples might be cited among invertebrates also.
Similar anticipations and verifications among the invertebrates have been made by Hyatt, Beecher, Jackson and others.
The polyphyletic law was early demonstrated among invertebrates by Neumayr (1889) when he showed that the ammonite genus Phylloceras follows not one but five distinct lines of evolution of unequal duration.
Among invertebrates similar analogous groups also develop. This is especially marked in retrogressive, though also wellknown in progressive series.
It is certainly a very striking fact that wherever we have been able to trace genetic series, either of invertebrates or vertebrates, in closely sequent geological horizons, or life zones, we find strong proof of evolution through extremely gradual mutation simultaneously affecting many parts of each organism, as set forth above.
Whereas among many ammonites and gastropods smooth ness of the shell, following upon an ornamental youthful Condition, is generally a symptom of decline, among many other invertebrates and vertebrates, as C. E.
Beecher (1856-1905) has pointed out (1898), many animals possessing hard parts tend toward the close of their racial history to produce a superfluity of dead matter, which accumulates in the form of spines among invertebrates, and of horns among the land vertebrates, reaching a maximum when the animals are really on the down-grade of development.
In general we find an analogy between the development of groups and of organs; we discover that each phyletic branch of certain organisms traverses a geologic career comparable to the life of an individual, that we may often distinguish, especially among invertebrates, a phase of youth, a phase of maturity, a phase of senility or degeneration foreshadowing the extinction of a type.
Jennings, Synopses of North American Invertebrates, xvii., "The Rotifera," Amer.
The importance of this resemblance between the Polyclad larva and the Trochosphere-larva of higher invertebrates is increased if the widely adopted V Ep (After F.
Smith on the Invertebrates of Vineyard Sound should be consulted (1874).
The fauna has been explored in great detail both as regards the vertebrates and the invertebrates, and specialists will find the necessary bibliographical indications in Travaux geographiques en Finlande, published for the London Geographical Congress of 1895.
Many insects and other invertebrates, mostly noxious, have been accidentally naturalized, and some have been deliberately introduced, like the honey-bee, now feral in Australasia and North America, and the humble-bee, imported into New Zealand to effect the fertilization of red clover.
All we can say is, that in those remote times what is now England had no existence; its site was occupied by seas which were tenanted by marine invertebrates, long since extinct.