ISOPODA. 113 



Subtvibe 2, Arcturidea (Anisopoda Idotaeica). 



Fam. 1, Arcturidas. — Subfam. 1, Arcturinse ; sub- 

 fam. 2, Anthurinae. 

 Subtribe 3, Tanaidea (Anisopoda Oniscica). 



Fam. 1, Tanaidce. — Subfam. 1, Tanainae ; sub- 

 fam. 2, Liriopinae ; subfam. 3, Crossurinae. 

 Fam. 2, Bopyridae. — Subfam. 1, Bopyrinas ; sub- 

 fam. 2, loniuEe. 

 Of the few divisions^ the names of which are printed 

 in italics, no representatives have hitherto been de- 

 tected in the British Seas. This is the more remarkable 

 as regards the entire parasitic family, Cymothoid.e, com- 

 posed as it is of three subfamilies. Of the remaining 

 extra British groups, the Ch^tilid.^ is composed of the 

 single genus Choetilia, Dana, with the sixth pair of legs 

 exceedingly long and multiarticulate, founded on a Pata- 

 gonia species ; the Tylin^ is composed of the spiracled- 

 branchial Tylos, Latreille, from the shores of the Medi- 

 terranean. The ScYPHACiN^, consists of the genera 

 ScyphaXj with one species from New Zealand, and Sty- 

 loniscus, with two species from Terra del Fuego and the 

 Friendly Islands ; the Ancinin^, of doubtful location, 

 is composed of the genus Ancinus, Edwards ; and the 

 SerolidtE, composed of the flattened genus Serolis, from 

 the Southern Seas, with strong claws to the fore legs. 



Of the subdivisions composing the three subtribes of 

 Isopoda proper we can speak with satisfaction ; but the 

 whole arrangement of the Anisopoda seems to us un- 

 natural : thus, referring only to the British groups, we 

 consider, 1st, that an arrangement which can group 

 together the female of Anceus (Praniza) and Serolis 

 must be founded upon entirely false principles. 2ndly, 

 that Arcturus, although exhibiting a remarkable modifi- 

 cation in its legs and basal segments of its tail, possesses 



VOL. II. I 



