244 



HUGH WATSON. 

 Text-fig. 6. 



Diagrams illustrating the rotation of the heart in the evolution of 

 carnivorous slugs from snails. 



A. Hyalinia, Rhytida, etc. B. Daudebardia. c. Apera. 

 D. Euglandina, etc. E. Strebelia. F. Testacella 



