Plate IX. 



Vol. IV. 



Helix p07natia. — i, Dart-sac and mucous glands natural size. 2, Dart, 

 3, 4, 5, 6, Abnormal growths of mucous glands. 7, Immature darts in three 

 stages X 4. 8, Base of dart approaching completion. 



Helix riifescens. — 9, Pair of bilobed sacs much enlarged, the darts shown 

 in position. 10, Pair of darts x 16. il, Anotlier pair. 12, Eggs passing 

 between the dart-sacs. 



Helix hispida, — 13, Pair of bilobed dart-sacs much enlarged. 14, Pair 

 of darts X 16. 15, Another pair. 16, Immature darts. 17, Union of mucous 

 glands in pairs. 



Helix concinna. — 18, Pair of bilobed dart-sacs much enlarged. 19, Pair 

 of darts x 16. 20, Another pair. 



