KUNGL. SV. VET. AKADEMIENS HANDUNGAR. BAND 48. N:0 1. 



21 



Adeorbis S. Wood 1842. 



Wliorls convex, tlic last large, ohlitiuely Hatteiied towards the aperture; umbilicus wide and deep, with 

 obtuse angular margin; colour reddish white. II. 1.7, D. 2 mm; Wh. 4 A. fragilis G. 0. Saks 1878. 



Archyta^a Costa 1869. 

 Tracliysma (Jeffreys M. S.) G. O. Sars 1878. 



Wliorls convex even at the aperture, not flattened below; und)ilicus deep, moderately wide without 

 ular border; colour transparent white. H. 1, 1). l.i nnn; Wh. 3 (G. U. ,Sars) 



A. delicatuni I'iuliiti 1844. 

 Shell more dilated, base somewhat flattened, aperture oblique. II. 1.2, D. 1.4 mm 



var. cxi)ansa G. 0. Saks 1878. 



