divisions of the animal and vegetable kingdoms are much less close
than the theory [of evolution] demands. Even the Archaeopteryx, the
discovery of which made so much stir and appeared to establish a genetic
relation between classes so distinct as Birds and Reptiles, fills up the
gap only imperfectly, and does not indicate the point of bifurcation of
these two classes. Intermediate links are lacking between Amphibia and
Reptiles. Mammals, too, occupy an isolated position, and no zoologist
can deny that they are clearly demarcated from other Vertebrates;
indeed, no fossil mammal is certainly known which comes nearer to the
lower Vertebrates than does Ornithorhynchus at the present day" (p.
115).

To take a parallel from the Invertebrata, B. B. Woodward,[545] after
discussing the phylogeny of the Mollusca as worked out by the
morphologists and comparing it with the probable actual course of the
evolution of the group, as evidenced by fossil shells, sums up as
follows:--"The lacunae in our knowledge of the interrelationships of the
members of the various families and orders of Mollusca are slight
however, compared with the blank caused by the total absence from
palaeontological history of any hint of passage forms between the classes
themselves, or between the Mollusca and their nearest allies. Nor is
this hiatus confined to the Molluscan phylum; it is the same for all
branches of the animal kingdom. There is circumstantial evidence that
transitional forms must have existed, but of actual proof none whatever.
All the classes of Mollusca appear fully fledged, as it were. No form
has as yet been discovered of which it could be said that it in any way
approached the hypothecated prorhipidoglossate mollusc, still less one
linking all the classes" (p. 79).

Pointing in the same direction as the absence of transitional forms is
the undeniable fact that all the great groups of animals appear with all
their typical characters at a very early geological epoch. Thus, in the
Silurian age a very rich fauna has already developed, and
representatives are found of all the main Invertebrate groups--sponges,
corals, hydroid colonies, five types of Echinoderms, Bryozoa,
Brachiopods, Worms, many types of Mollusca and Arthropoda. Of
Vertebrates, at least two types of fish are present--Ganoids and
Elasmobranchs. In the very earliest fossiliferous rocks of all, the
Precambrian formation, there are remains of Molluscs, Trilobites and
Gigantost