22 



NILS ODHNEE, NORTHERN AND ARCTIC INVERTEBRATES. III. OPISTHOB R A N OH I A ETC. 



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

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



PI. II tigs. 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 (Müller 1776). 



PI. m fig. 10. 



Issa Bergh 1880. 



I. The marginal papilla? short, about 25 — 28 on each side, the dorsal ones occur in 

 about 4 longitudinal rows, their length = V 2 of the marginal papilla? ; the posterior 

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

 gills sulphureous. L. 44 mm. I. lacera (Abildgaard 1806). 



II. The marginal papilla? numerous, about 50 on each side, rather long, reaching to 

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

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

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



I. villosa n. sp. 

 PI. I fig. 21. 



Thecacera Fleming 1828. 



(Jills 5, surrounded by a ring of obtuse tubercles: sheaths of the rhinophores simple. Colour pale 

 reddish yellow marbled willi green: rhinophores and gills green, these latter white in the margins. Radula 

 5.2.0.2.5. L. 8 nun. T. virescens Aldek & Hancock 1855. 



Palio Gray 1857. 



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

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

 cles. Colour greenish or yellowish : papilla? yellow. L. 20 mm. 



P. Lessoni (d'ORBiGN y 1837) = ocellata (Alder & 

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

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

 (Möller 1842). 



PI. II tig. 1(3. 



Polycera Cuvier 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 papilla? yellow; gills, rhinophores and posterior 

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

 L. to 20 mm. P. quadrilineata (Müller 1776) = cornuta (Abildgaard 1806). 



PI. Ill tigs. 11—14, 



