206 



G. H. PARKER 



When such specimens were brought into the laboratory and 

 studied closely in a glass aquarium, the details of their locomo- 

 tion could be readily made out. In this operation the foot and 

 body musculature is the active part. As compared with other 

 moUusks, the foot of Strombus is rather peculiarly shaped. 

 Anteriorly it has the form of a broad, flattened finger which can 

 be applied very closely to the substrate (fig. 1). Behind this 

 comes a second portion which is smooth and rounded from side 





%:!:m 



Fig. 1 Ventral view of the foot of Strombus gigas. A, anterior flattened 

 end; B, middle rounded portion; C, posterior or metapodial portion carrying the 

 operculum, D. 



Fig. 2 Outline of a lateral view of a stromb immediately after a leap. The 

 dotted outline indicates the general position of the parts before the leap, the full 

 outline after the leap. A, anterior end of the foot; B, operculum; C, shell. 



to side; this part is seldom in close contact with the surface over 

 which the snail is moving. Finally, in the posterior region the 

 foot tapers off, carrying at its hind end the long, dark-brown, 

 pointed operculum. This metapodial portion is thrust vigor- 

 ously into the ground at each spring of the animal. 



When an active stromb is put on its side in a glass aquarium, 

 it soon begins to protrude its foot and eye-stalks. At the least 

 movement on the part of the observer it is likely to withdraw 

 into its shell and with a suddenness quite surprising for a snail. 



