20 



COM PA RA TI VE A NA TOM Y 



CHAP. 



Fig. 29.— Teredo Navalis in its boring, 

 ventral aspect (after Meyer and Mobius). 

 The centre is omitted, tlie calcareous tube 

 is for the most part uninjured. 



3-V 



t~\ 



\~- 



Fio. 30.— Shell of Aspergilliim (Bre- 

 chites) vaglniferum, dorsal view, o, An- 

 terior; p, posterior; d, right; i:, left; 1, 

 siplional aperture of the pseudoconch ; 2, 

 pseudoconch (calcareous tube) ; 3, true shell 

 embedded in the pseudoconcli ; 4, anterior 

 aperture of the pseudoconch. 



