380 The Molluscan Family Planorbidae 



PLATE 72 



Acrorbis petricola Odhner 



Copied from Odhner's paper in Arkiv. for Zoologi, Band 29B, Xo. 14, 

 two plates redviced to one plate in this volume. 



1-3. Acrorbis petricola Odhner. Shell from below, front view, and from above. 



4. Radula, one-half row on left side. X 1000. 



5. Animal removed from shell to show organization, from above. 



6. Head and foot of animal, fore view. 



7. Buccal sac. 



8. Digestive system, from above. 



9. Penial complex. 



10. Portion of genitalia. 



Description of symbols used on this plate: a, flagellum (anhangsdrlise) ; 

 b, spermatheca (bursa copulatrix) ; c, caecum, a blind sac; d, intestine; 

 f, tentacle; g, ganglia in nerve collar; go, ovotestis (gonad); h, heart in 

 pericardium; j, jaw; k, pseudobranch (kiemen falte) ; I, liver; m, stomach; 

 n, kidney (niere) ; o, oesophagus; od, oviduct (in the figure this refers to 

 the ovisperm duct) ; p, prostate; ph, buccal sac; ps, preputium (penissack, 

 here including the whole penial complex, preputium and vergic sac) ; 

 r, rectum; rp, penial retractors; s, salivary glands (speichel driisen) ; 

 t, radula sac (radula tasche) ; u, uterus; v, vas deferens. 



