SEA STAES AND STAEFISHES. 53 



equal in size, some being as large as grapes, while the 

 others scarcely equal peas in dimensions. 



Whatever may be the nature of the contents of the 

 vesicles, it seems to have the power of penetrating 

 between the shells and paralysing the addiictor muscles. 

 The shells are thus forced to open, and the Starfish then 

 pushes the vesicles between them, and absorbs into its 

 own digestive system the whole of the oyster except the 

 adductor muscle. 



A French naturalist, who was watching the ebbing 

 tide, observed a number of odd-looking, ruddy balls 

 rolling along as the water receded. On approaching 

 them, he found that each ball was composed of five or 

 six Five-finger Starfishes, all with their rays interlaced. 

 On opening the balls he found that within each of 

 them was a Trough-shell (Mactra stultorum), and that 

 the Starfishes were ranged round it so that their mouths 

 came in contact with the edges of the shells. In every 

 case the shells were slightly open. 



It might be thought that by dissection a keen observer 

 might have detected the deadly vesicles ; but no sooner 

 is the Starfish detached from its prey than the vesicles 

 collapse, and, large as they were when dilated, leave not 

 the slightest trace of their existence. 



