EXPLANATION OF PLATE XVL 



Fici. I. Lainellidens marginalis, showing the various organs diagram- 

 matically. Nat. size. 



,, 2. Solenaia soleniformis, showing the various organs diagram- 

 matically. Nat. size. 



,, 2 a-d. Vertical sections through Solenaia solenijormis showing the 

 relation of the glandular and non-glandular sacs (dia- 

 grannuatic). 



„ 2 c. Diagram of the communication of the glandular and non- 

 glandular sacs — 



1. Opening of the non-glandular sac into the accessory canal. 



2. Cut edge of the mantle lobe. 



3. Attached margin of the membrane to the outer wall of the 



canal. 



4. Attached margin of the membrane to the inner wall of the 



canal. 



5. Cut edge of the mantle. 



,, 3. Phf/sunio jernKjineus, nat. size, shell and mouth of the left side 

 removed. 



,, 3 rt. P. ferrugineus, showing the various organs diagrammatically. 



,, 4. P. micro'pter aides, nat. size, shell and mantle of the left side 

 removed. 



The attachments of the gills are represented by interrupted lines. 



