2 NILS HJ. ODHNER 



Nudibranchs are concerned, some forms which are either new 

 to science — 3 new species are established here — or but little, 

 imperfectly or incorrectly, known with regard to their anatomy 

 and systematical position. In the last case I have tried to supply 

 these déficiences by giving completing descriptions and figures. 

 I also take this opportunity of expressing some points of view 

 as to the problem on the affinities of, and among, the Nudi- 

 branchia. 



In order to avoid the publishing of a mere list of species 

 and localities, and to increase the faunistical value of the state- 

 ments of occurrence I have added accounts of number and 

 dimensions (length in millimetres) of the specimens obtained, 

 which should be a desideratum in similar cases, because it often 

 leads to conclusions of greater reach, than does a mere list of 

 mere names. 



The collections are chiefly made by Prof. G. 0. Sars, as 

 already mentioned; in other cases the collectors are stated. Here, 

 some forms also are included which have been collected in the 

 Kristiania Fjord by Dr. Kiaer, though the comprehensive 

 results of these dredgings are intended for a special report. 



The nomenclature employed in this paper is with a few 

 exceptions the same as was used in my work of 1907^. 



Tectibranchia.. 



Fam. Actaeonidae. 



Actaeon tornatilis Linné. Herlø våer, 20—30 fms, 1 sp., I. 

 15 (det. as „Tornatella fasciata Lam."). 



Fam. Tornati'nidae. 

 Retusa pertenuis Mighels. Vadsø, 6 ex., max. 1. 2. 



1 Norttiern and Arctic Invertebrates in ttie coll. of the Swed. State 

 Mus. Ill Opisthobranchia and Pteropoda. K. Sv. Vet. Akad. Handl. 

 Bd. 41 no. 4. 



