256 WM. E. RITTER. 



Normal School, first called my attention to the fact that the protru- 

 sion of the proboscis occurs only while the sand is uncovered dur- 

 ing low tide ; that withdrawal takes place almost immediately upon 

 the incoming of the tide. My own observations confirm this. I 

 have several times searched the ground in which the animals are 

 abundant, when it was covered by a few inches only of still, 

 clear water, and have never .under such conditions seen a single 

 extruded proboscis. The meaning of this habit is not clear. 



Movements of both boring and locomotion are effected in the 

 enteropneust through a combination of ciliary and muscular ac- 

 tion. When crawling about on the surface of objects, which it 

 does with considerable facility, the ciliary method is chiefly, 

 though by no means exclusively, depended upon. When boring, 

 or moving up and down its canal, muscular action is on the other 

 hand most used. 



The best way to observe the movements is to allow the ani- 

 mals to bury themselves in sand contained in a glass vessel. 

 Under such circumstances they are certain to move along the 

 inner surface of the glass if the vessel be small (a test-tube or 

 homeopathic vial, for example, I have found favorable), for a 

 portion of the time, and the whole operation may then be easily 

 watched. 



By far the most vigorous activity in any portion of the animal, 

 both ciliary and muscular, goes on in the proboscis. The ciliary 

 action is seen to best advantage when the animal is moving 

 about on a sandy surface on which there are small elevations with 

 which the tip of the proboscis comes in contact now and then ; 

 for the creature does not readily bring its proboscis tip into 

 contact with a perfectly even surface on which it may rest. As 

 the end of the proboscis touches the slope of a sand hillock, a 

 perfect flood of sand grains is at once started which soon wholly 

 encircles the organ and passes rapidly back to the collar. Ar- 

 rived here the rapidity of the flow is greatly lessened so that if 

 the picking up of grains at the tip be prevented a girdle of sand 

 is soon formed around the collar. 



If, on the other hand, the acquisition of grains be not inter- 

 rupted the whole proboscis and collar become coated by a con- 

 tinuous sheath of sand which gradually extends backward until 



