Miscellaneous. 177 



of which about 80 have been found for the first time by me. The 

 total number of animals of the Caspian at present known must 

 be more than 150. If this fauna is poor in comparison with those 

 of other seas, such as the Mediterranean and even the Black Sea, my 

 researches prove that it is much richer than it has hitherto appeared ; 

 and the assertion of Yon Baer, that " whoever chooses to be led away 

 by his mihusmus to establish new species must elevate slight varieties 

 to the rank of species," unfortunately* appears not to be justified. 

 This is especially evident if we consider that this sea has even now 

 been but little examined, particularly in its deepest parts, where 

 animal life seems to be manifested most intensely. The water of the 

 Caspian being poor in saline constituents, it is in the deep parts that 

 its composition most nearly approaches that of sea-water. 



T intend giving you only the most general results of my researches 

 as they appear at present before the study of the animals collected 

 has been terminated, and even, I may say, at the moment when I 

 am commencing it. 



In its fauna the Caspian presents the characters of a great half- 

 salt lake which possesses its own peculiar species of animals, and 

 also contains others which occur in other seas. The former (e. g. 

 the new Gohius and Benthophili) originate from living or already 

 extinct species, or they result from slight modifications of allied 

 species living in other seas, as is the case with Corer/onus hucichthys, 

 Calictis caspia, Eichw. (which is a good species), Petromi/zon Wagmri, 

 Kessl., Tintinnus mitra, sp. n., and Renlera fltva, sp. n. The other 

 animals (that is to say, those which occur also in other seas) possess 

 a great tenacity of life, since they still prosper where their less robust 

 ancient colleagues have long since died out : in this category we 

 place liotcdia veneta, Sahellkles octocirrata, L'trjuncula repeas, Mysls 

 relicta, and Idothea entomon. 



These species common to different seas show the affinities of the 

 Caspian Sea to the Aral Lake, the 'Black Sea, and the Arctic Ocean ; 

 but the affinities wdth the glacial sea seem to be more recent than 

 those with the Black Sea ; for in the latter certain species, such as 

 the seals, Coregonus leucichthi/s, and others which are common to 

 the Caspian and glacial seas, are wanting, "We may suppose that 

 in the Tertiary epoch there existed in Europe and in the neighbour- 

 ing parts of Asia a vast closed basin of fresh water. By an upheaval 

 of the crust of the earth, due to the action of the volcanic forces which 

 still make themselves felt energetically in the region of the Caspian, 

 this was separated into some smaller basins, which arc the existing 

 Black Sea and the Aralo-Caspian basin. The latter in its turn was 

 afterwards divided into two, just as we still see small salt lakes 

 separate from the Caspian. At the same time the water of the 

 glacial sea penetrated into the basin of the Caspian, which still had a 

 slight connexion with the Black Sea, so that only a small number of 

 animals could arrive there from the glacial sea. Hence we find 



• I say '' unfortunately,' hecau^o I do not like new species, and yet 

 find myself compelled to establish a considerable number. 



