A number of species of Cyclopidae and Cypridae, many of which are blind and colourless, have been brought up in well-water. The Amphipod _Niphargus puteanus_ has long been known from a similar source in England[170] and all over Europe, and several other blind Gammarids inhabit the subterranean waters and caves in various parts of the world. Among Isopods, _Asellus cavaticus_ is recorded from wells and caves in various parts of Europe, _Caecidotea stygia_ and _C. nickajackensis_ from the Mammoth and Nickajack Caves in America, and two very remarkable blind Isopods are described by Chilton from the subterranean waters of New Zealand, viz. _Cruregens fontanus_, whose nearest allies are the marine Anthuridae, and the Isopods _Phreatoicus typicus_ and _P. assimilis_, which bear an extraordinary resemblance superficially to Amphipods. Besides these, a small number of subterranean Decapoda are known which retain the eye-stalks but are without functional ommatidia. These are _Troglocaris schmidtii_, in Hungary, related to the fresh-water Atyid _Xiphocaris_ of East Indian and East Asiatic fresh waters rather than to the South European _Atyephyra_; _Palaemonetes antrorum_, from artesian wells in Texas; and several species of _Cambarus_ from the Eastern United States. A blind species of _Cambarus_, _C. stygius_, has been described from the caves of Carniola, and if this determination is correct, is the sole _Cambarus_ occurring outside America. It will be seen from the above account that the subterranean Crustacea are an exceedingly interesting and, in many respects, archaic group, many of which have survived in these isolated and probably uncompetitive districts, while many secular changes were going on in the quick world overhead. The remaining fresh water =Malacostraca= may be mentioned under the headings of the groups to which they belong. Only one “Schizopod,” apart from _Paranaspides_, is known from fresh-water lakes, viz. _Mysis relicta_, which was discovered in 1861 by Lovén in the Scandinavian lakes, and has since been found in the Finnish lakes, the Caspian Sea, Lake Michigan, and other localities in N. America, and Lough Erne in Ireland. This species is closely related to _Mysis oculata_ of Greenlandic seas. In the Southern Hemisphere we have a species of _Anaspides_, _A. tasmaniae_, occurring in mountain streams and tarns in Tasmania, a related form which haunts the littoral zone of the Great Lake in Tasmania, and a small species, _Koonunga cursor_, occurs in a little stream near Melbourne. Of the Isopoda certain genera, viz. _Asellus_ and _Monolistra_, are confined to fresh water, others, such as _Sphaeroma_, _Idothea_, _Alitropus_, and _Cymothoa_, have occasional fresh-water representatives. Packard[171] describes a remarkable blind Isopod, _Caecidotea_, from the Mammoth Cave of Kentucky, which occupies a very isolated position, and in the same work gives a very complete exposition of the cave-fauna of North America and Europe.