TUBE OF PANTHALIS. 177 



on its back, with about i an inch of the forepart of its 

 body projecting from the opening most recently made. 

 During the night it had searched round the mouth of 

 the old tube for a distance of about an inch, and had 

 lined the new mouth of the burrow with " cobwebs." 

 In the course of the following twelve hours it partially 

 buried this cobweb with mud which it had drawn in at 

 the opening, and it was evidently commencing a solid 

 tube. It also now shewed great activity by burrowing 

 under, and violently upheaving the mud at the opposite 

 end of the burrow, with the object of making a second 

 opening in that direction, which it ultimately accom- 

 plished. I therefore watched it until 11 p.m. and made 

 a careful sketch of the floor of the tank, in order to 

 observe any change which might take place during the 

 night. Just before leaving, I found that a considerable 

 amount of " cobwebbing " had been done during the 

 evening, and I saw the animal, for the first time, reverse 

 its position in the burrow, by doubling upon itself ventrally. 

 On returning to the aquarium at 7 o'clock next morning, 

 I found Panthalis, as usual, with its head just at the new 

 mouth of the burrow, to which, it had, during the night, 

 added a piece of tubing between the glass of the tank, and 

 the opening of the old tube ; the material for which had 

 been obtained by digging a hole about ^ inch diameter 

 and \ of an inch deep, in the mud close by. As no food 

 had yet been supplied, I now attempted to feed Panthalis 

 by offering it a small red marine worm ; but this caused 

 alarm, and as the worm intended for food commenced to 

 burrow into, and I feared would destroy the new piece of 

 tube, I at once removed it. Panthalis had, the while, 

 retreated into its burrow, but in course of about ten 

 minutes returned ; forced its head slowly and carefully 

 through the mouth of the new tube, and proceeded to 



