XVIII] 



MOVEMENTS 



387 



water and laid upon damp sand it is incapable of burrowing and 

 wriggles helplessly about. As soon however as it is covered by 

 water the proboscis and collar are seen to dilate and become stiff, 

 and the proboscis is then inserted into the sand, soon followed by 

 the collar, whilst the trunk is dragged passively after them. As 



..3 



FIG. 182. A Dolichoglossus kowalevskiixl. From Spengel. 

 Proboscis. 2. Collar. 3. Trunk. 4. Mouth. 5. Gill-slits. 



the walls of both proboscis and collar are highly muscular the 

 water can be expelled through the pores and the volume of these 

 regions of the body diminished, but the action of the cilia soon 

 swells them up again. On the hinder wall of the proboscis cavity 

 there is a puckered membrane richly supplied with blood-vessels, 



252 



