There are other creatures which stand in solitary isolation, with no fragments of a bridge to connect them with the general body. Such is the rattlesnake's family, whose pedigree, Mr. Mivart declares,[261] we cannot even imagine--"The ancestors of the rattlesnake are beyond our mental vision."
But the number of forms [says the same author][262] represented by many individuals, yet by _no transitional ones_, is so great that only two or three can be selected as examples. Thus those remarkable fossil reptiles, the Icthyosauria and Plesiosauria, extended, through the secondary period, probably over the greater part of the globe. Yet no single transitional form has yet been met with in spite of the multitudinous individuals preserved. Again, with their modern representatives the Cetacea, one or two aberrant forms alone have been found, but no series of transitional ones indicating minutely the line of descent. This group, the whales, is a very marked one, and it is curious, on Darwinian principles, that so few instances tending to indicate its mode of origin should have presented themselves. Here, as in the bats, we might surely expect that some relics of unquestionably incipient stages of its development would have been left.
Professor W. C. Williamson likewise remarks[263] on these _lacunæ_ which persistently occur at crucial points:
If [he writes] these generic types [of plants] first came before us in such clearly defined forms, when and where did the transitional states make their appearance? The extreme evolutionists constantly affirm of those who believe in special creation that they "habitually suppose the origination to occur in some region remote from human observation," and that "the conception survives only in connexion with imagined places where the order of organic phenomena is unknown." It is legitimate to retort upon them that they as habitually resort to "strata now covered by the sea"--to rocks "from which all traces of such fossils as they probably included have been obliterated by igneous action," and to mysterious "migrations from pre-existing continents to continents that were step by step emerging from the ocean." Unfortunately, so far as the vegetable kingdom is concerned, we have as yet failed to discover any traces of these mysterious strata or hypothetical continents in which the transitions from one plant-type to another were being brought about. The believers in special creations are not the only reasoners who have made free use of hypothetical possibilities.