Having thus hastily glanced at the slender fauna of the rocks immediately below the Cambrian, we may now proceed to inquire a little more in detail into its true value and import as leading toward the beginning of life. I have already referred to the apparently sudden drop in the number of groups and of species below the base of the Cambrian, and have hinted that this may be an effect of temporary local conditions of deposit or of defective information. Another fact that strikes us is the diverse and miscellaneous character of the fossils that remain to us; and this would suggest that we are either dealing with a mere handful picked at random, as it were out of a richer fauna, or that in the beginning of things the gaps and missing links between different forms of life were even more pronounced than at present. This, however, would be likely to occur if the plan of creation was to represent at first different types, with few forms in each; to produce, in short, a sort of type collection representing the whole range of organization by a few characteristic things rather than to give a complete series, with all the intermediate connections. Such a mode of introduction of life is not _à priori_ improbable, however at variance with some prevalent hypotheses. Beginning with the higher Invertebrates, we must not conclude that we have altogether lost the Trilobites. The fragments referred to this group may represent at least a few species, and it would be very interesting to know more of these as to their relations to their successors, and whether they are tending to lower or more embryonic forms. The bivalve Crustaceans (Ostracods) may be regarded as inferior in rank to the Trilobites, but are still very complex, and specialized animals and a specimen silicified in such a manner as to show the interior organs testified that, as far back as the Carboniferous at least, these creatures were as highly organized as at present,[11] while their generally larger size in the earlier formations tends to show that they have rather been degenerating in the lapse of geological time. [Footnote 11: _Palæocypris Edwardsi_, Brougniart, Coal Formation of St. Etienne, France.]