THE TAIL. 237 



parallel to the body, in order to project the faecal 

 refuse to the anterior extremity of the tube, he 

 ascribes a similar structure to the present species. 

 " In A. auricoma," he observes, the tail-like appen- 

 dage to the inferior extremity of the body, in all 

 respects but one, is formed on the model of that of 

 the former species. One labium of the terminal 

 orifice is here extended into a flap-like process, which, 

 by a sudden act of muscular contraction, imparts a 

 smart blow to the faeculent mass as it escapes from 

 the intestine, and thus effectively conveys it to the 

 upper outlet of the tube." (p. 208). Again, in treat- 

 ing of the alimentary system of the genera Serpula, 

 Sabella and Amphitrite, he remarks that " it is 

 through the agency of the water-current that traverses 

 the whole interior of the body, that the faeculent 

 refuse is projected from the bottom to the upper 

 orifice of the tube, and that the habitation of the worm 

 is maintained in a state of never-varying cleanliness 

 and purity." (p. 225). 



I am absolutely certain, however, that in my speci- 

 men of A. auricoma the discharge is terminal. As 

 the animal lies on the bottom, a stream of water 

 issues from the hinder end of the tube, not constant 

 but intermittent, by which the adjacent sand is driven 

 away with force, forming a furrow, a third of an inch 

 long, extending from the end of the tube. The ter- 

 minal portion of the tail itself is occasionally protru- 

 ded through the aperture, and moved round with 

 agility. When the tube with the contained animal is 

 removed from the water and again replaced, a bubble 

 of air escapes from the posterior orifice; and when the 



