22 NILS ODHNER, NORTHERN AND ARCTIC INVERTEBRATES. III. OPISTHOBRANCHIA ETC. 



dish brown with dark-brown spöts, which in the centre are greenish blue and shining. 

 L. 15 mm. Ae. pnnctilucens (d'ORBiGNY 1837). 



Pl. II figs. 9—10. 



Triopa Johnston 1838. 



Margin-processes in the front 8, granulated, the central ones smaller, on the 



sides 6 or 7, cylindrical and smoother; the middle of the back with tubercles: gills 3, 



tripinnate. Colour white, the dorsal tubercles and the tips of gills and processes orange 



or red. L. 18 mm. T. clavigera (Muller 1776). 



Pl. III tig. 10. 



Issa Berc4h 1880. 



I. The marginal papillse short. aboiit 25 — 28 on each side, the dorsal ones occur in 

 about 4 longitudinal rows, their length = V^ of the marginal papillse ; the posterior 

 end of the foot (behind the mantle) very short. Colour white; rhinophores and 

 gills sulphureous. L. 44 mm. I. lacera (Abild&aard 1806). 



II. Tlie marginal papillse numerous, about 50 on each side, rather long, reaching to 

 the outer row of the dorsal papillae ; these set in about 6 rows and varying in 

 size, mostly longer than the marginal ones; the posterior end of the foot nearly 

 == Ve of the body in length. Colour (in alcohol) yellowish white. L. to 48 mm. 



I. villosa n. sp. 



Pl. I iig. -21. 

 Thecacera Fleming 1828. 



(tUIs 5, saiTOuiidcrt by ;i ring of obtuse tubercles: .slieatbs of the rliiiiopbores simple. Colour påle 

 reddi.sli yellow luarbled witb greeii ; rhinopbore.s and gills greeu, tbese latter white in the margins. Piadula 

 5.2.0.2.5. L. 8 mm. T. virescens Aldek & Haxcock 1855. 



Palio Gray 1857. 



Head-margin with numerous (8—16) short lobes or conical papillse; mantle- 

 margin with many short processes at the gills : the wliole body covered with tuber- 

 cles. Colour greenish or yellowish : papillas yellow. L. 20 mm. 



P. Lessoni (d'ORBiGNY 1837) = ocellata (Ålder & 

 Hancock 1842) = pudica, modesta, plebeia (Lo- 

 ven 1846) = dubia (M. Särs 1829) = ?Holbölli 

 (Möller 1842). 



Pl. II lig. 16. 



Polycera Cdvier 1817. 



Head-margin with 4 long, digitiform processes; mantle-margin with one process 

 at each side of the gills ; along the back and the sides 4 — 9 rows of tubercles. Co- 

 lour white ; tubercles and anterior papillae yellow ; gills, rhinophores and posterior 

 processes with yellow ends; body sometimes with black or orange longitudinal bands. 

 L. to 20 mm. P. cjuadrilineata (Muller 1776) = cornuta (Abtldgaard 1806). 



Pl. m tigs. 11 — 14. 



