44 



On the Habits of the Amphictenidse. 



the side of a glass vessel ; further off another is ejecting waste 

 material from the narrow end of its tube. 



Whether each tube is the lifework of its tenant, or the tubes 

 are shed from time to time, as has been suggested, is an open 

 question ; but I am strongly inclined to the former view, for 

 the following; reasons : — 



(1) Their construction is, as one would naturally expect 



of such beautiful workmanship, very slow, so far as 

 I have been able to judge. 



(2) In many tubes the small end is so minute that it was 



evidently formed when the animal was very much 

 younger. 



(3) The tube gradually increases in diameter towards the 



mouth or growing edge (as in the tubes of other 

 annelids and shells of some moUusks), so that there 

 would appear to be no necessity and but little advan- 

 tage in shedding the tube ; while, on the other hand, 

 there would be, unless we assume a complicated 

 method of change, the great disadvantage of a 

 lengthened exposure of the delicate helpless body of 

 the worm. The fact mentioned by Prof. M'Intosh in 

 a paper recently contributed to the ' Annals and 

 Magazine of Natural History ' ^, viz. that " the 

 smaller end of the tube has grains considerably finer 

 than the wider upper end," would also appear to 

 support my view. 

 Sheffield, 

 June 8, 1894. 



* Vide ser. 6, yol, xiii. p. 14. 



