32 NILS ODHNteR, NORTHERN AND ARCTIC INVERTEBRATES. III. OPISTHOBRANCHIA ETC. 



B. Rhinophores < the oral tentacles. 



1. Radula with 13 — 20 rows. 



a. Radula as in C. rufibranchialis but the apices of the lam. lat. curved 

 inwards; papillse in 4 — 5 dusters, the first of 16 — 18 gills; rhinophores 

 somewhat corrugated. Colour transparent white, with 3 longitudinal 

 opaque white lines ; papillse rose-coloured, at the tops white-ringed ; a 

 white line runs along the rhinophores, the tentacles, the branchiae, the 

 back and each side. L. 25 mm. C. lineata (Loven 1846). 



pi. m fig. 2<i. 



b. Radula with the lam. med. at each side with 4—5 denticles, the lam. 

 lat. with 8 — 10 ones ; papillae in 4 dusters, with 12 — 14 papillae in the 

 front, 10 in the 2nd, and fewer in the back dusters ; rhinophores smooth. 

 Colour transparent white, at the back yellowish green; papillae orange- 

 coloured, with a white ring below the tips. L. 14 mm. 



C. gracilis (Ålder & Hancock 1844*). 



2. Radula with 26 — 27 rows; lam. lat. with 6 denticles, lam. med. with 5 ones 

 on each side; rhinophores smooth; papillae in 5—6 dusters with 4, 3, 2, 

 1 rows resp., of 2 — 3 papillse each. Colour violet, gills orange-red, with 

 white tips; rhinophores and oral tentacles violet with white ends. 

 L. 8,5 mm. C. Landsburgi (Ålder & Hancock 1846^')- 



C. Rhinophores > the oral tentacles; radula with 15 — 27 rows; lam. lat. with 

 12—13 denticles, lam. med. with 5—7 ones on each side; rhinophores slightly 

 wrinkled; papillae in dusters and rows (of these about 20 — 30 on each side), 

 each containing 2 — 3 papillse. Colour (in alcohol) light yellowish brown, on 

 the back towards the end with dense white spöts; papillae with white tips. 

 L. 9—18 mm. C. bostoniensis Bergh 1864. 



II. Papillae in irregular transverse rows; body broad; anterior angles of the foot 

 only a little produced. 

 A. Laterals of the radula serrated on the margin. 



1. Anus in front of the middle of the right side; radula with 20 rows; lam. 

 med. with 6 — 9 denticles on each side, lam. lat. with 8 — 9 ones; papillae in 

 close rows with 4—6 each, subcylindrical, transparent; body (in alcohol) 

 semitransparent. I*. 16 — 24 mm. C. Sarsi Friele 1902. 



2. Anus in or behind the middle of the right side. 



a. Radula with 10 — 12 denticles on each side of the lam. med. and 9—13 

 (Särs) or 13—26 ones (Bergh) in the lam. lat. Body broad; head expanded 

 at the sides, as broad as the anterior part of the body ; rhinophores 

 a little less than the oral tentacles; gills very short, elliptical. Body, 

 rhinophores and tentacles påle reddish. L. 13 — 29 mm. 



C. salmonacea (Couthouy 1839). 



b. Lam. med. of the radula with 5 denticles on each side; lam. lat. with 

 6 ones; body slender, tapering towards the end, broader than the head; 



