CRUSTACEA MALACOSTRACA. II. 



area is more difficult to define, btit it may be proposed that the stations with a depth 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 exclusivel}.' 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 aiiuiuahis G. O. S., l^scudotanais affinis H. J. H., Typlilo- 

 taiiais iiiixtus n. sp. Lcptognatliia loiigirriiiis Lilljeborg, L. voitralis n. sp., L. brrvirciiiis Lilljebg., 

 Cryptocopc arctica H. J. H. and Sfrongylura cyliiidrafa G. O. vS.) 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 [Typlilotatiais niixtus) all these species have besides been takeu 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 freqixently less than 

 100 fathoms. Some few species (as Leptognafhia hicnnis n. sp., L. Sarsii H. J. H., L. sicbccpialis n. sp. 

 and I., laiirctnis 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. suba^qualis 

 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 Apseudidse 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 Apseiidcs spii/osiis 

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

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

 the thoracic segments, the pleopods and their setse are longer, the flagella of the antennulfe and 

 antenna; 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 Tanaidjc 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 Norwa\-, but he was acquainted 

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

 Flcttrotauais Oerstcdii Kr., Typhlotanais fiitinarchicus G. O. S., Parafaiiais Batei G. O. S. and Lrpfognathia 

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

 males of Aiiarthrura simplex G. O. S. and Pscudotanais forcipafiis Lilljebg., hul his animals were only 

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

 described, without figures, b\- Lilljeborg) is wideK different from the subadult stage. Sars was aware 

 that his males of Sfroiigylitra cyliiidrala G. < ). S. were "probably" immature, which in reality was 

 the case, hi 1885 he figured the adult male of Cryptocope Voringii G. O. S.; in his paper on the 

 Mediterranean forms he figured the adult males of Lcptognatliia brcviiiiaiia Lilljebg., Urtcrotanais 



