1922. No. 5. ARIONIDAE OF NORWAY. 53 



Var. media Jensen should be rejected; without doubt there is a confusion 

 with the young of Ar/'o// atcr (p. -aQ, foot-note). 



In Norway the species has been found up to 1250 m. above sea level, 

 in large specimens up to a length of 7 — 8 cms. (Finse station, Bergens- 

 banen). 



Results in Avion circumscriptus. 



Arion hortensis of Birgithe Esmark and of O. S. Jensen (as of We- 

 sterlund) in reality is Arion circiiinscriptus (p. 32). 



As regards the reproductive organs the following facts should be 

 mentioned : the receptaculum may have all transitions in the shape of the 

 bladder between those with a marked appendix to those where no rudi- 

 ments of the latter are to be seen (fig. 26 — 33); the branch of the retractor 

 for the oviduct may be absent, as a rule, however, being represented 

 by one or a few slender fibres (fig. 26 — 28, 31, 33). The best specific 

 character is the long, ribbon-shaped atrium (fig. 26 — 28). hi the Norwegian 

 stock orificiuni genitale is situated a little anterior to the split leading to 

 the respiratory aperture (fig. i). The spermatophore has now been found 

 (p. 36, fig. 34). 



Var. nigra no v. var. Animal dark grey to bluish black; the back, 

 and especially the shield, with little black points. Mucus on the lower 

 part of the sides milky white. Occuring together with var. circumscripta 

 nom. nov. in many localities (p. 37, PI. I, 5). 



Ah. flava nov. ab. Pale yellow, lowest part of the sides pale. A 

 single specimen at Toien, Kristiania (p. 37, PI. I, 6). 



The most northern locality of the species is Kinn, Kvæfjord on 

 Hinnö (p. 38). 



The measurement of about 800 living specimens proved that all stages 

 of development occur simultaneously throughout the year; only three of 

 them were as large as about 5 cms. 



Results in Arion hortensis. 



The genital retractor may arise as a continuous muscle or be separated 

 in branches. The genital atrium is either more or less transversally con- 

 stricted or practically with no transverse furrow (p. 43, fig. 40 — 41). 



The northern limit of the species is now known to be Kristiansund, 

 about 63 north, lat. Other reliable Norwegian localities are: Molde, Aale- 

 sund, Florö and Kristiania (p. 44); all the previous statements of its occur- 

 rence in Norway are false or uncertain. 



Results in Arion intermedins. 



In the Norwegian stock the genital orifice is situated in the prolonga- 

 tion of the split to the respiratory aperture, in contrast to the foreign 

 ones, where it is described as having a far more anterior position. Accord- 



