articulation found in the spiders and the mites! The supposition that the number of twenty segments was decided on for the three groups of superior _Articulata_ for the mere sake of adhering to a pattern is doubtless unphilosophical. But it is not unphilosophical to suppose that whatever amount of articulation is found in each species was given to it because in that species it would be useful. If in some of the most aberrant orders of these animals the articulation is greatly obscured, or not found at all, the conclusion that it was not needed, or not needed in a like degree, is far more rational than the theory which commits the particular result to an infinity of chances against it; or which supposes it to have been worked by a process that might have produced a very different result, since it can not be claimed that natural selection works by methods of which any definite result can be predicated more than another. Thus far I have considered Mr. Spencer's argument from the _Articulata_ in the light of the facts that he adduces. Let us now test it by the absence of facts. In a former discussion, I have asked for facts which show, aside from the theory, that any one species of animal, distinctly marked as a continuing type, is connected by intermediate types or forms with any pre-existing race of another character. Take this class of the articulated animals, said to be of hundreds of thousands of different species having no community of form but this of articulation, and now known as perfect organisms, each after its kind. What naturalist has discovered the continuity of lives with lives, which would furnish the steps of descent of any one of this species from an antecedent and a different species? It is very easy to construct a theory, and from it to argue that there must have been intermediate links, which, if discovered, would show the continuity of lives from lives which the descent of one organism from another necessarily implies. To a certain extent, within certain limits, the sub-groups and the sub-sub-groups of the articulated class of animals, which classification or morphology reveals, may lay the foundation for a theoretical belief in an ancestral stock from which the different and now perfect forms of these distinct animals may have become developed by successive changes of structure. But the extent to which connected changes can be actually traced in the animal kingdom is extremely limited; and the important practical question is whether any one fact, or class of facts, has been discovered which will warrant the belief that beings of totally dissimilar forms and habits of life have, without any design, been evolved by the ordinary process of successive generation, through the operation of causes that have gradually modified the structure in all respects save one, and have at the same time enabled or allowed that one peculiarity of structure to escape from the influences which have modified both structure and modes