TANAIDACEA AND MARINE ISOPODA FROM JUAN FERNANDEZ 533 



Remarks. 



Tanais lineatus is characterized by its chelipeds, which have the free 

 distal margin of the propodus very sHghtly curved, almost straight. This is 

 also the case in T. novae- zealandiae Thomson and T. temiicornis Hasvvell, but 

 the first species is distinguished by its well-marked ciliated bands on the first 3 

 abdominal segments, and the second species has its carapax very much longer, 

 almost as long as the first 4 free thoracic segments. 



A nearly .straight propodal edge on the chelipeds is shown also by T. 

 Nierstrassi Stebbing, which differs especially in having the first 3 thoracic 

 segments very short. 



The species nearest to T. lineatus seems to be the T. Normani Richard- 

 son from California. From that species T. lineatus differs chiefly in its somewhat 

 more slender chelipeds, with longer carpus and a nearly straight propodal edge. 

 The resemblance between these 2 species is, however, so great that it is pos- 

 sible that they may be shown to be identical. T. Normani Rich, is not known 

 in detail and only from 3 apparently immature specimens. The conclusion 

 that T. lineatus is identical with T. Normani is therefore too hasty; the adult 

 males and females may very possibly turn out to be much less similar. 



Order ISOPODA. 



Suborder Flabellifera. 



Fam. Anthuridae. 



Genus Paranthura Bate and Westwood 1868, Barnard 1925. 



Paranthura Skottsbergi n. sp. — PI. 20, fig. 4; text fig. 5. 



One specimen, immature female, length 11 mm; 



Loc. Juan Fernandez, Masatierra, calcareous algae, 30—46 m. 



Description. 



Head subrectangular, about twice as long as it is broad. The rounded ante- 

 rio-lateral corners anteriorly more produced than the minute rostrum. Anterior 

 margin bisinuated with a small triangulate apex (rostrum) between the anten- 

 nae. The eyes are large, dark brown, rounded, and composed of about 24 ocelli. 



Thorax. Increases in breadth to the 6th segment. The 4th segment is 

 the longest, the 6th is about as long as the ist. The 7th segment is a little 

 more than half of the length of the 6th and about as long as the abdomen 

 without telson. The last 3 thoracic segments dorsally with an impressed 

 line a short distance from the anterior margin. 



The ventral side of thorax is strongly elevated and keeled. On the first 

 2 segments the keel has a narrow edge, but on the following segments up to 

 the 5th the edge widens to a flattened surface, which in the 6th and 7th seg- 

 ments diminishes in width. 



