EXPLANATION OF PLATE IL 



Fig. I. — Animal of Solen kempt, Preston, ventral view, X 2, 



,, 2. — Animal of 5. kempt, Preston, anterior view, X 3. 



„ 3. — Posterior view of 5. kempi, Preston, X 3. 



„ 4. — Animal of 5. kempt, side view (a) and (6), X 3. 



,, 5. — Posterior portion of S. kempi, showing retractor 

 siphonis muscle, X 3. 



„ 6. — Animal of S. gravelyi, side view, X 3. 



,, 7. — Animal of S. gravelyi, posterior portion showing re- 

 tractor siphonis muscle, X 3. 



^, 8. — Ventral view of S. gravelyi, X 3. 



,, 9. — Semi-diagrammatic section of the visceral mass of S. 



grave/yi. 



„ 10, — Animal of 5. sp. from Japan, side view, X 10. 



„ 1 1. — Section of visceral mass of S. sp. from Japan, showing 

 the alimentary canal. Semi-diagrammatic. 



„ 12. — Neosolen aquae-dulcioris , ventral view, X 2. 



