54. Tanaidacea and Marine Isopoda from Juan Fernandez. 
By 
AKE NORDENSTAM. 
With Plate 20 and 12 text figures. 
Through Professor CARL SKOTTSBERG the task has been confided to me 
of describing the Tanaidacea and marine Isopoda collected during his expedition 
(1916—17) off the Juan Fernandez-Islands by Dr. K. BACKSTROM. For this 
kindness I express to Professor SKOTTSBERG my best thanks. I also wish to 
thank my friend Dr. N. ODHNER at the Natural History Museum (Riksmuseum) 
in Stockholm for having facilitated my work in various ways. 
The material consists of 10 species, of which not less than 7 are new. 
Of only one of the new species, Lanocira hirsuta, there are plenty of indi- 
viduals. 4 new species, Adega dicavata and 3 species of Paranthura, must be 
described from only one specimen each, and of the remaining 2 new spe- 
cies, Zanazs (Anatanais) marmoratus and /ineatus, there are unfortunately no 
full grown individuals. I regret that owing to these circumstances the descrip- 
tions are necessarily imcomplete. 
For the drawings and photographs illustrating this paper I am indebted 
to Mr. S. EKBLOM and Mr. C. SVEDEN. 
Order TANAIDACEA. 
Fam. Tanaidae. 
Genus Tanais Audouin and Milne Edwards 18209. 
Subgenus Anatanais n. subgen. 
The large number of species belonging to TZanazs are clearly to be 
divided into two groups, one Zanazs s.s. with 5, the other with 6 free abdom- 
inal segments. Both STEBBING (1905) and (NIERSTRASZ) 1913 regard this diffe- 
rence as of almost generic value. As later investigations have failed to discover 
transitional forms, I completely agree with this view, and I propose for the 
forms with 6 free abdominal segments the new subgeneric name of Axatanats. 
In 1914 VANHOFFEN gave a list of species of Zanazs described up to 
that year. From his group of Zanazs with 6 free abdominal segments 7. 
Stanfordi Rich. (cf. RICHARDSON 1901) should, however, be removed. In the 
34—29232. The Nat. Hist. of Juan Fernandez and Easter Ist. Vol. III. 
