In one particular Professor Dawkins's views differ from those of almost all the previous writers. His connection between the Caspian and the Arctic Ocean is placed to the west of the Ural Mountains, while it had always been assumed by the Russian writers to have lain on the eastern or Asiatic side of that mountain range. Thus, when Tcherski in recent years announced that the tract on this eastern side of the mountains was covered by freshwater deposits, his discovery seemed once for all to settle the problem of the arctic marine connection in the negative. As Professor Dawkins's theory has, however, received much additional affirmative evidence by current faunal researches, a connection between the Caspian (or Aralo-Caspian) and the Arctic Ocean (White Sea) may have actually existed within recent geological times. What _relict lakes_ are, has already been explained (p. 176), and their fauna will again be referred to in a subsequent chapter. I might perhaps be allowed to repeat that such lakes are supposed to have been flooded by, or to have been in close connection with, the sea at some former period. Many of the Swedish lakes are spoken of as relict lakes (Reliktenseen), because they contain a number of marine species of animals which have now become adapted to live in fresh water, but all of whose nearest relatives inhabit the sea. One of these, the schizopod crustacean _Mysis relicta_,--a shrimp-like creature,--which was formerly believed to inhabit also the Caspian, is of particular interest. More recently, the occurrence of this _Mysis_ in the Caspian was denied, but though this denial has been confirmed by Professor Sars in his memoir on the crustaceans of the great Russian inland sea, he has been enabled to add two new species of _Mysis_ to the list of those already known to science. These are _M. caspia_ and _M. micropthalma_, and both are closely related to the arctic marine _Mysis oculata_. According to Professor Sars, the genus _Mysis_ as a whole may be regarded as arctic in character. The occurrence of these two species, therefore, in his opinion, points to a recent connection of the Caspian with the Glacial Sea. A large number of other crustaceans have been described by the same author from the Caspian. Of the order Cumacea, which is exclusively marine, ten species are mentioned, but none of these seems to range beyond the Caspian. Among the smaller species of crustaceans, a minute pelagic copepod (_Limnocalanus grimaldii_) also inhabits the Baltic and the Arctic Ocean. The marine isopod _Idotea entomon_, related to the common wood-louse, has a similar distribution. Genuine Arctic species of Fishes do not seem to occur in the Caspian, though some, viz., _Clupea caspia_, _Atherina pontica_, _Clupionella Grimmi_, and _Syngnathus bucculentus_, are almost certainly the descendants of marine forms.