32 



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



B. Rhino phores < the oral tentacles. 



1. Radula with 13 — 20 rows. 



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

 inwards; papillae in 4 — 5 clusters, the first of 16 — 18 gills; rhinophores 

 somewhat corrugated. Colour transparent white, with 3 longitudinal 

 opaque white lines; papillae 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. 0. lineata (Loven 1846). 



PL in fig. 26. 



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

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

 front, 10 in the 2nd, and fewer in the back clusters; 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 (Alder & Hancock 1844 a ). 



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 clusters with 4, 3, 2, 

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

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

 L. 8,5 mm. C. Landsburgi (Alder & 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 clusters and rows (of these about 20—30 on each side), 

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

 the back towards the end with dense white spots ; 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. L. 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 

 (Sars) 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 pale 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; 



