1898.] Pack-BkrKSFOrd. — Tube-Forming Larvcs. 5 



accommodating as to make their burrows beside the glass, so 

 that I was able to watch them ver}^ easily and to study their 

 mode of procedure. 



Having worked the hole underground to their satisfaction, 

 they proceeded to search all round the mouth for building 

 materials, and a regular tube was then built up bj^ impercep- 

 tible degrees over the mouth of the burrow, the whole being 

 about half as long again as the animal inhabiting it. In 

 some cases the tubes were nearl}^ all underground, in some 

 about half and half, and in some the tubes were made alto- 

 gether above the level of the mud, sometimes on the side of 

 the glass, at others on bits of sticks or grass. I have since 

 found these tubes on the sides of a cemented tank several 

 inches above the bottom. These lar^^se are voracious feeders, 

 like all their kind, and I found that if I put a dead leaf or 

 bit of decaying grass into the bottle, they nearly all came out 

 of their tubes and did not leave the leaf till they had picked 

 it clean, when they returned home. 



I could not be certain that each animal invariably returned 

 to his own burrow, though in many cases I was able to watch 

 they certainly did so. Sometimes, too, they would leave 

 their holes and wriggle to near the surface of the water, 

 where they would stop for some little time before going down 

 again. 



Although it is believed that these excursions are made for 

 the purpose of breathing air, I could never make out that they 

 did so, as they were never still for a moment. The waving mo- 

 tion of their bodies was kept up, even when deep down in 

 their tubes, and seemed to be used to keep the water in circu- 

 lation, and assist respiration, which is believed to be carried 

 on by means of the two pairs of appendages on the last ab- 

 dominal segment but one, and the shorter appendages on the 

 last segment. 



The caterpillar-like appearance of the creatures — the head 

 provided with short antennae and strong biting mandibles — the 

 pair of sucker-feet with circles of hooks, on the first and also 

 on the last segment of the body— stamps them at once as 

 larvae, and distinguishes them clearly from annelids of similar 

 habits. I was not, therefore, surprised to see them gradually 

 become less and less vigorous in their movements and even- 

 tually turn into pupae, which after a time wriggled out of their 



