Family 2. _Polydesmidae._ Two species in amber. Family 3. _Lysiopetalidae._ A number of species, amongst which are 6 _Craspedosoma_, mostly from amber. {77}Family 4. _Julidae._ A number of species of this family have been found, some in amber, some in other Tertiary strata. Amongst the latter a probable example of _Julus terrestris_, living at the present time. Family 5. _Polyxenidae._ Five species have been found in amber. Now that we have considered the structure of the Myriapods and the groups into which they are subdivided or classified, we may proceed to consider what position they hold in the household of nature. That they present certain features of similarity to other classes has been already mentioned, and that this is the fact cannot be doubted when we look back at the way in which they have been classified in the works of early writers. For example, Lamarck, the great French naturalist, classifies them with spiders in his well-known work, _La Philosophie Zoologique_, under the name of _Arachnides antennistes_. Cuvier, the comparative anatomist, unites them with the Insects, making them the first Order, while the Thysanura is the second. We have already seen that one Order of Myriapods, the Symphyla, bears a great resemblance to the Thysanura. The English naturalist Leach was the first to establish Myriapods as a class, and his arrangement has been followed by all naturalists after his time. But while their peculiarities of structure and form are sufficiently marked to separate them as a class, it cannot be denied that the older naturalists were right to recognise that they have many essential characteristics in common with other classes of animals. And recent investigations have emphasised this fact. For instance, let us consider the recent discoveries of the Orders of Symphyla and Pauropoda, Orders which, while bearing so many of the characters of Myriapods that naturalists have agreed to place them in that class, yet resemble in many important points the Insect Order of Thysanura. This seems to justify Cuvier in claiming the close relationship for them that he did.