24 NILS ODHNEE, NORTHERN AND ARCTIC INVERTEBRATES. III. OPISTHOBRANCHTA ETC. 



3.1.0.1.3 (Alder & Hancock 185 1») or 5.1.0.1.5 (G. O. Sars 1878), with the 

 laterals denticulated. Colour white or yellow. L. about 30 mm. 



A. pilosa (Müller 1776) = tomentosa (Loven 1846). 



P II tigs. 13—15. 



Colour brown or blackish var. fusca (Loven 1846). 



PI. IT fig. 12. 



II. Gills 15, simply pinnate: rhinophorial orifice slightly crenelated; papilla? close, 

 nearly cylindrical; radula 3.1.1.1.3, the laterals smooth. Colour whitish or 

 dirty yellow. L. about 30 mm. A. sibirica (Aurivillius 1887). 



A da] aria Bergh 1879. 



I. Papilla? club-shaped; radula 10. 1 . 0. 1 . 10. Body semi-transparent, white or yellow. 



L. 14—25 mm. A. proxima (Alder & Hancock 1845 a ) = echinata (Loven 1846). 

 11. Papilla? broadly rounded; radula 12.1.1.1.12 (Sars 1878). 1 Colour yellowish 

 white. L. 20 mm. The biggest papillae at the middle and along the sides of the 

 back, smaller ones on the margins, interspersed with minute ones all over 



A. Loveni (Alder & Hancock 1862) 

 = Doris muricata Müller of Loven 1846. 



Lamellidoris Alder & Hancock 1855. 



1. Radula with lamina media: (1— 2) . 1 . 1 . 1 . (1— 2) . 



A. Radula 1.1.1.1.1; gills 20 — 30; lam. lat. not denticulated, papilla? verruci- 

 form. Colour yellowish, marbled with brown on the back. L. 25 mm. 



L. bilamellata (Linne 1766). 

 Gills 16 var. liturata (Möller 1842). 



B. Radula 2.1.1.1.2; lam. lat. minutely serrated (denticles 15—20); gills 11; 

 papilla? club-shaped or rounded. 



1. The under side of the pallial margin smooth; papilla? uniform in size; co- 

 lour yellowish. L. 10 — 13 mm. L. muricata (Müller 1776). 



2. The underside of the mantle furnished with close -set papilla?. Body 

 semi-transparent. L. 10 mm. L. aspera (Alder & Hancock 1842). 



3. The underside of the pallia! margin with a few papilla? and with y- 

 shaped lines; body transparent (the intestines showing through). Colour 

 white. L. c. 10 mm. L. diaphana (Alder & Hancock 1845 b ). 



II. Radula without lamina media: 1.1.0.1.1. 



A. Laterals of the radula denticulated, uniformly arched and furnished with a 

 strong hook near the apex. 

 1. Gills 9. 



a. Apertures of the rhinophores lobated; papillae obtuse, rather sparse. Colour pale yellow with 

 distinct brown spots. L. 7 mm. L. sparsa (Alder & Hancock 1846 11 ). 



b. Apertures of the rhinophores smooth; papilla? short, conical, close-set. 

 Colour brown. L. 9 mm. L. pusilla (Alder & Hancock 1845 1 '). 



1 The lam. med. wanting according to Alder & Hancock 1862; formula in Friele & Hansen 1876: 



