NORWEGIAN OPISTHOBRANCHIATE MOLLUSCA 45 



Dolo, it must be derived from a primitive type which had it 

 well perfected. 



As regards all the genital characters, as a whole, we must 

 refer Doto to a type more primitive than the Aeohds and the 

 Tritonias, more primitive, too, than the Ascoglossa, which re- 

 present an off-spring into a separate direction towards a triaulic 

 organization, while Doto is derived from a type with a wide 

 ampulla and retaining prostala at the same time as vesicula 

 seminalis. It does not seem impossible to refer the Dotonidae 

 to forms which were ancestors also of Lobiger; from the same 

 source the Ascoglossa may have originated, and thus we are 

 able to explain the similarities in the organization of the two 

 different families. 



Fam. Pleurophyllidiidae. 



Pleurophyllidia lovéni Bergh. Farsund, 1 sp., 1 8— Aas- 

 gaardstrand, 10 — 12 fms, 1. 16 (det. as „Diphyllidia horealis 

 Sars == lineata F. & H."). 



Ascoglossa. 



Stiliger mariae Meyer & Møbius. Korshavn, 4 sps., max. 1. 2. 



Elysia viridis Montagu. Rennesø, 7 sps., max. 1. 7 — 

 Farsund, some small sps.— Raegefjord, 10—15 fms, some small sps. 



Limapontia capitata Müller. Hammerfest, 6 sps., max. 

 L 3.5 — Manger, on Confervae, many sps., max. I. 4 - Far- 

 sund, 1 sp., 1. 3.5. 



