Anatomy/ of the Ventriculites of Mantel* 



335 



form of the animal, this spongious surface only is exhibited : 

 but, upon its full expansion, numerous openings appear in all 

 parts of the surface, regularly arranged in a quincuncial order ; 

 and in silicipus casts form the papillae described by Mr. 

 Mantel. I have been so fortunate as to procure some spe- 

 cimens exhibiting the inner surface uninjured, see figs. 93. and 

 94?. Fig, 93. is a magnified view of a fragment of a contracted 



specimen : a shows the inner surface, not covered with the 

 openings or mouths of the tubes ; b shows that those tubes 

 are formed in that portion, appearing on its outer surface, and 

 probably becoming exposed on its inner surface when the 

 structure becomes unfolded by expansion or distention. The 

 figures are magnified views of one fragment ; a the inner 



surface, and h the surface broken from the substance of the 

 body. Fig, 94. exhibits the fossil in about a half degree of ex- 

 pansion ; a portion of the mineralised animal is seen at the 



z 4 



