PLATE XXV. 



FIGS. 



1. Nolgula ralvata sp. nov. (p. 49) Mantle, showing- 

 alimentary canal : four times natural size. 

 2 and 3. Nolgula simplex A. & H. (p. 51) Mantle: three 

 times natural size. 2. Right side, showing diges- 

 tive organs. 3. Left side, showing reproductive 



organs. 



4-6. Nolgula siphonata Alder, (p. 63) 4 and 5. Mantle, 

 showing digestive and reproductive organs (4, left 

 side; 5, right side) : one and a half natural size. 

 6. Mantle laid open, exposing branchial sac, etc. : 

 a little more enlarged, gn. genital outlet. 



