1922. No. 5. 



ARIOXIDAE OF NORWAY. 



35 



Fig. 28. Lower parts of the reproductive organs of Arion circninscriptus, ^,1. 

 atr. atrium genitale, ep. epiphallus, o. oviduct, o.-sp.-d. ovispermatoduct, rec, receptaculum, 



retr. retractor, v. d. vas deferens. 



ree 



Fig. 29— 31. Receptacula oi Arion circuniscriptits, '/l. 

 o. oviduct, rec. the bladder of the receptaculum, reir. retractor. 



subfiiscits. It may be added that the degree of filling influences the shape 

 of the bladder, which especially is highly extended when containing a 

 spermatophore (fig. 33). 



The genital retractor {retr. I is also of va^3^ng development. It insérâtes 

 at the stalk of the receptaculum, but often has a rudimentary branch to 

 the oviduct, with point of insertion at the middle of the latter, or a little 

 lower. Generally this branch is only represented bv one or a few thin 

 fibres, and may easily be overlooked (fig. 26 — 28, 31, 33). 



