lo: 



removed. The pericardial space witli the included parts, has 

 taken up a position postcriu.- .^ thn ^.'i.ii.^i ,, • :.,3cle. The 

 secondary caecim of the stomach has been fonned. The ciUs 

 project beyond the visceral mass, x 190, 



Fig. 8, Adiilt , from left side. Tho two extensions of 

 the mantle over the shell shown on thn dorsal side of the 

 latter. The mantle also extends over the posterior margin of 

 the shell for a short distance. The siphons ai"e represented 

 as fully extended, but the palettes not quite fully retract- 

 ed. The mantle extends over the bases of the palettes as a 

 collar . The attachjiients of the muscles of the palettes and 

 siphons are shovm. The drawing v^as made from a slirtitly con- 

 tracted specimen 10 cm. long. 



Fig. 9. Same as S, the mantle removed to its line of at- 

 tachjtient dorsally, at tlio two ends, to the midline. 



Fig, 10. Adult, anterior half of the body, with the left 

 shell valve, mantle and gill removed, and the pericardial 

 cavity laid open. }Ialf of the posterior adductor removed. 



Fig, 11, Ri^ht^ and fig, 1?., left shell valves of newly- 

 attached larva, internal vicv/. Tlie rudimentary apophyses are 

 shown below the teeth, x 220, 



Fig. 13, Shell of newly-attached larva, end view, x 220- 



.Fig, 14. Shell of "Sh.ip-worm" that has been in the wood 



