The fishes of the deep sea have been the subject of extensive monographs by L. Vaillant (_Travailleur_ and _Talisman_), A. Günther (_Challenger_), A. Alcock (_Investigator_), R. Collett (_Hirondelle_), S. Garman (_Albatross_) and a general résumé up to 1895 was provided in G. B. Goode's and T. H. Bean's _Oceanic Ichthyology_. More than 600 true bathybial fishes are known from depths of 1000 fathoms and more, and a great deal of evidence has been accumulated to show the general transition of the surface fauna into the bathybial. A recent departure has been the exploration of the Antarctic fauna. Three general reports, on the results of the _Southern Cross_, the _Belgica_ and the Swedish _South Polar_ expeditions, had already been published in 1907, and others on the _Scotia_ and _Discovery_ were in preparation. No very striking new types of fishes have been discovered, but the results obtained are sufficient to entirely disprove the theory of bipolarity which some naturalists had advocated. Much has been done towards ascertaining the life-histories of the fishes of economic importance, both in Europe and in North America, and our knowledge of the larval and post-larval forms has made great progress. Wonderful activity has been displayed in the field of palaeontology, and the careful working out of the morphology of the archaic types has led to a better understanding of the general lines of evolution; but it is to be regretted that very little light on the relationships of the living groups of Teleosteans has been thrown by the discoveries of palaeontologists. Among the most remarkable additions made in recent years, the work of R. H. Traquair on the problematic fishes _Palaeospondylus_, _Thelodus_, _Drepanaspis_, _Lanarkia_, _Ateleaspis_, _Birkenia_ and _Lanasius_, ranks foremost; next to it must be placed the researches of A. S. Woodward and Bashford Dean on the primitive shark _Cladoselache_, and of the same authors, J. S. Newberry, C. R. Eastman, E. W. Claypole and L. Hussakof, on the Arthrodira, a group the affinities of which have been much discussed.