78 POLYCERID.E. 



also when properly looked for. Its range extends northward 

 to Norway and Sweden. [Heligoland (Erey and Leuckart) ; 

 Kiel Bay (Meyer and Mobius).] 



Genus VII. IDA'LIA*, Leuckart. 



BODY ovate, thick, rather convex, with a small indistinct 

 mantle occupying an elevated dorsal area, and margined with 

 filaments, which are longest in front of the tentacles : dorsal 

 tentacles linear, laminated, non-retractile, without sheaths : 

 head broad, produced in front, without oral tentacles : gills 

 simply pinnate, non-retractile : foot large : odontophore narrow, 

 with four spines in each transverse row : there is a spinous 

 buccal collar. 



The aspect of Idalia is rather heavy and massive compared 

 with other members of the family ; but it is generally attrac- 

 tive on account of the beauty and variety of its colours, the 

 prevailing one of which is red. Members of the genus are 

 found throughout most of the European Seas. 



A. Centre of the back furnished with filaments . 

 1. IDALIA E'LEGANS, Leuckart. 



I. elegans, Leuck. Brer. An. Desc. p. 15, f. 2; A. & H. Brit. Nud. Moll. 

 fam. 1, pi. 27. f. 1-4. 



BODY ovate, a good deal elevated on the back, white, thickly 

 freckled with rosecolour, the processes of a brilliant orange- 

 yellow : mantle small, the margin with two long filaments in 

 front of the tentacles ; filaments round the sides numerous 

 and rather short, the posterior ones on each side obtusely 

 lobated ; dorsal filaments five, three down the centre and one 

 on each side in front of the gills ; they are all bright orange 

 with yellow tips : dorsal tentacles long, linear, finely laminated 

 behind for about two-thirds down, rosecoloured, with a central 

 pale band and yellow tips : head broad, sloping downwards 

 from the tentacles : gills or branchial plumes 18, raised on a 



* A name of Venus. [Properly Idalie.] 



