On the Habits of the Amphictenidse. 43 



X. — On the Habits of the Amphictenidae. 

 By Arnold T. Watson. 



Although the marine Annelids of this group are well known 

 as the skilful architects of tapering cylindrical tubes of fine 

 sand, there appears to be a difference of opinion amongst 

 naturalists as to their mode of life ; and it may therefore be 

 of interest to record my own observations. Some authorities, 

 for instance, speak of the smaller end of the tube as found 

 uppermost, projecting from the sand, which is doubtless, as 

 we shall see, its normal position. Others, however (Pallas 

 amongst them), describe this position as reversed, the small 

 end buried and the wider one, which is occupied by the 

 animal's head, exposed, or, at all events, close to the surface. 

 This at first sight does not seem unnatural ; but when we 

 understand the object of the comb-like head-bristles, whose 

 function, so far as I am aware, has not previously been 

 explained, the vertical position, with the wide end exposed, 

 is seen to be a most disadvantageous one, and, excepting 

 under accidental or occasional circumstances, must be con- 

 trary to the habit of the worm. 



I have at different times had several specimens of Pecti- 

 naria or Lagis under observation, and in all cases, when left 

 undisturbed, the worms buried themselves more or less com- 

 pletely in the sand, entering it by digging with their combs 

 (as with a fork), and making a passage through which the 

 wide portion of the tube first passed, followed by the narrower 

 part, the extremity of which was frequently left projecting 

 from the sand — the refuse from the animal being expelled 

 through the small end of the tube, which is usually inclined 

 to the surface of the sand, the small end uppermost. As 

 these worms are great travellers, the position varies some- 

 what, and the tube may occasionally assume the horizontal 

 or even the vertical position ; but in all cases the large end 

 is the advancing one. The head-bristles or " golden combs " 

 are used not only for the purpose of digging, but also probably 

 for sifting the sand, thus enabling the animal to select food 

 and suitable material for building. This is evident from the 

 eager way in which the tentacles explore the fresh ground 

 laid open in the cavity formed by each " toss " of the animal's 

 head. The digging is continuous throughout the day, and it 

 is therefore probable that the worm does not, as at present 

 supposed, confine its building operations to the night-time. 



The accompanying sketch shows the creature, natural size 

 partially submerged in the sand and working close against 



