CRI'STACHA MALACOSTRACA. II. 



area is more difficult to define, but it may be proposed that the stations with a deptli between 300 

 and 600 fathoms and the bottom temperature not below 3 , and all stations with depth from 600 to 

 1870 fathoms and the temperature above zero belong to that area. When we adopt this view it will 

 be found that about 38 species enumerated in the following pages were taken exclusively in this 

 warm deep-sea area, which consequently has a much richer fauna than the cold deep-sea area. A 

 somewhat small number of species (Sphyrapus anomalus G. O. S., Pseudotanais a (finis H. J. H., Typhlo- 

 tanais mixtus n. sp. Leptognathia longiremis Lilljeborg, L. ventralis n. sp., L. breviremis Lilljebg., 

 Cryptocope arctica H. J. H. and Strongylura cylindrata G. O. S.) have been taken both in the real cold 

 deep-sea area and at rather deep or very deep stations in the warm area; but with a single 

 exception [Typhlotanais mixtus] all these species have besides been taken in depths of less than 

 100 fathoms either by the "Ingolf" or at Norway, at East Greenland or in the Kara Sea. The 



majority of the remaining species are forms living in depths less than 300 and frequently less than 

 100 fathoms. Some few species (as Leptognathia inermis 11. sp., L. Sarsii H. J. H., L. subeequalis n. sp. 

 and L. latiremis n. sp.) cannot be referred to any of the three categories just mentioned, but they seem 

 to be essentially cold water forms sometimes found in temperatures a little above zero; L. subeequalis 

 was once taken even in 318 fathoms in a temperature of 3.9 . 



C. Sexual Differences in the Tanaidae. 



Adult males of species of the family Apseudidae are frequently taken together with the 

 females, and I am unable to add anything to our knowledge of the sexual differences in this family. 

 Sars has published excellent figures of both sexes of the two Norwegian species Apseudes spiuosus 

 M. Sars and Sphyrapus anomalus G. O. S., of Sphyrapus serratus G. O. S. and of a few species of 

 Apseudes from the Mediterranean. In the males the abdomen is generally longer in proportion to 

 the thoracic segments, the pleopods and their seta; are longer, the flagella of the antennulse and 

 antennae and the endopod of the uropods are longer and divided into a larger number of joints than 

 in the females; furthermore, the chelipeds of the males differ somewhat or very much from those 

 of the females, and sometimes the second pair of thoracic legs show some difference. 



As to the family Tanaidae our knowledge of the males is still very imperfect and some inter- 

 pretations are erroneous; it is necessary to distinguish sharply between adult and subadult or immature 

 males. Sars has described the females of 26 species of Tanaidae from Norway, but he was acquainted 

 with really adult males of only 5 species, viz. Tanais Cavolinii M.-Edw. (T. tomentosus Kr., G. O. S.), 

 Heterotanais Oerstedii Kr., Typhlotanais finmarchicus G. O. S., Paratanais Batci G. O. S. and Leptognathia 

 Sarsii H. J. H. [L. longiremis G. O. S., not Lilljeborg); he described also what he believed to be the 

 males of Anarthrura simplex G. O. S. and Pseudotanais forcipatus Lilljebg., but his animals were only 

 subadult males, not adult specimens, and at least the adult male of the last-named species (already 

 described, without figures, by Lilljeborg) is widely different from the subadult stage. Sars was aware 

 that his males of Strongylura cylindrata G. G. S. were "probably" immature, which in reality was 

 the case. In 1885 he figured the adult male of Cryptocope Voringii G. * >. S.j in his paper on the 

 Mediterranean forms he figured the adult males of Leptognathia brevimana Lilljebg.. Heterotanais 



