46 



whence it radiates to be attached to the side of the cal- 

 careous tube along a broad line, its orip;in. On cither 

 side tliere are two retractors of the palette. One is in- 

 serted on the end of the handle and passes forwards to be 

 distributed in the mantle' along the sides of the body. 

 The other is inserted near the outer end of the handle, 

 whence it runs forwards to be attached alone with the si- 

 phonal muscles. The adductor is a stout, cylindrical mus- 

 cle, stretching between the anterior ends of the palette 

 handles, and lyinr; in the septum which divides the mantle 

 cavity posteriorly. The muscles of the siphons are at- 

 tached on either side along a triangular area to txie cal- 

 careous tube, sliglitly anterior and ventral to the attach- 

 ment of the palette muscles. From tiiis origin the siphon- 

 al muscles arc distributed to the siphons , mostly to the 

 respiratory. 



The action of the muscles of the palettes and si- 

 phons is as foll07/s:- When the "Ship- worm" is undicturbe4 

 the siphons are widely extended, as represented in fig. 21. 

 If disturbed in any vmy , the siphons are retracted with 

 great rapidity by the contraction of their muscles. At 

 the same time, by the action of the pi'Otractors of the 



