CRUSTACEA MALACOSTRACA. II. 



tanais G. O. S. with 16 species, Leptognathia G. O. S. with 14 species, Pscudotanais G. O. S. with 

 5 species, Cryptocope G. O. S. with 4 species, Haplocopc G. O. S. with 2 species, Strongylura G. O. S., 

 Anarthrura G. O. S., Mesotanais Dollf., Pancolus Richardson, Tanaissus Stebb., Tanaella Norm. & Stebb. 

 and Bathytanais Beddard, each with a single species. In all 18 genera with 107 species. 

 Thus the order Tanaidacea comprises 26 genera with about 149 species. 



Results and Questions. 



A. The "Ingolf" Collection. 



According to the literature only 9 species have hitherto been known from the coasts of Green- 

 land and the adjacent deep-sea area; the number of deep-sea species secured North of L,at. 56 N. by 

 the English expeditions was small, and the excellent collector of small Crustacea Prof. G. O. Sars 

 captured only 8 species of Tanaidacea during the Norwegian North-Atlantic Expedition. Judging 

 from these and other facts every zoologist would have thought it to be a good result if the "Ingolf 

 had raised the number of species known from the seas around our northern dependencies to twenty 

 or possibly twenty-five. But as already stated, the "Ingolf captured 71 species of Tanaidacea, some 

 other expeditions or travellers added 6 species, and a single deep-sea species enumerated in the 

 literature as taken by the "Valorous" within the area in question was not found again. - Besides it 

 may be stated, that a good number of the new species were taken by the "Ingolf at several stations 

 and sometimes in considerable numbers. 



Of the 78 species only 8 belong to the Apseudidae, but 70 to the Tanaidse. The animals 

 belonging to the Apseudidae are on the whole considerably or much larger than the Tanaidae and 

 consequently far less overlooked by collectors. But as only 8 species - - 3 among them new of 

 Apseudidae were secured by the ''Ingolf and the "Thor", while 42 species are described in the literature 

 from all seas together, the number of species from our northern area is not even one-fifth of species 

 hitherto established. As to the Tanaidse the result is very different; 106 species were known from 

 all seas, but the "Ingolf, etc. captured 70 species, thus almost two-thirds as many as hitherto known. 

 And 49 species of the Tanaidae are new to science. 



These excellent results are mainly due to a method of collecting introduced by me during 

 the first "Ingolf" cruise. A considerable quantity of the mud hauled up by dredge or trawl, or the 

 whole bottom material when its quantity was less considerable, was sifted under water in smaller 

 portions in a sieve clothed with silk gauze 110.7 use ^ by millers; the well-sifted contents of the sieve 

 were put in alcohol and later examined at home in small portions, in water or alcohol, on the lower part 

 of a cheese-cover under a moderately magnifying lens. In this way hundreds of small animals, as 

 Tanaidacea, Asellota. etc., were gathered. Other deep-sea expeditions could certainly have arrived at 

 corresponding results if their methods of dealing with the bottom material had been more satisfactory; 

 it may be considered quite certain that hundreds of species of small Crustacea etc. lived in the bottom 

 materials hauled up by the "Challenger" and later great European and North American expeditions 



and were flushed into the sea again. 



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