PLATE XLII Continued. 



FIG. 30. Spirorbis eancellatus (Fabricius), p. 248. Bottom view of a calcareous 

 plate. 



31. Nearly front view of same. 



32. Operculum showing calcareous plate becoming detached. 



33. Back view of fig. 31- 



34. Opposite view of fig. 32. 



All figures by the author, X 43- 



(343) 



