240 NAKED MOLLUSCA. PART m. 



naked body are capable of being withdrawn into a cavity 

 in the medial line of the back, and are either plumose, or 



Fig. 174. Whelk. 



like the leaf of a plant pinnated again and again, but 

 they vary in form and position in the different genera. 



Fig. 175. The Crowned Eolis. 



In the group of the Eolidse, the gills are like leafless 

 trees in most genera, but in the principal genus Eolis, 

 they are long, spindle-shaped, sharp-pointed papillse, 

 arranged in transverse rows or clusters along the sides 



