8 MARINE ANIMALS OF MASSACHUSETTS BAY. 



of expansion and contraction. Fig. 2 represents it with all its 

 external appendages folded in, and the whole body flattened ; in 

 Fig. 3, the tentacles begin to steal out, arid the body rises slightly ; 

 in Fig. 4, the body has nearly gained its full height, and the ten- 

 Fig. 2. Fig. 3. Fig. 4. 



tacles, though by no means fully spread, yet form a delicate 

 wreath around the mouth ; while in Fig. 5, drawn in life size, the 



Fig. 5. 



Figs. 2, 3, 4 Actinia in different degrees of expansion. (Ayassiz.) 



Fig. 5. The same Actinia (Metridium marginatum) fully expanded ; natural size. 



