TUBE OF PANTHALIS. 187 



Explanation of Plates. 



Plate IX. 



Fig. 1. Longitudinal section of wall of tube of Panthalis. 

 Sketch (slightly enlarged) made from portion of 

 tube sectionised under water to shew the series of 

 layers thrown outwards. The darkest part (b) is 

 the inside of the tube. 



Fig. 2. Sketch of Panthalis in its burrow, shewing it in 

 a very frequent position, viz., twisted so as to 

 expose the front ventral, and posterior dorsal parts. 

 The palps extend in front ; the buccal tentacles 

 almost meet in the form of a Y, and the ventral 

 bloodvessel, with its broad front, runs horizontally 

 towards the rear. The cobweb first formed, is 

 indicated to the right of the burrow, and at the 

 opposite end is seen the remnant of the cobweb, 

 by means of which (mingled with mud) the new 

 tube was made. The opening of the new tube is 

 shewn as a little mound (a) at the left of the 

 picture. The old tube forms the mass above the 

 burrow. 



Fig. 3. Enlarged sketch. Ventral view of anterior por- 

 tion of Panthalis shewing the two long palps (a) 

 (ends broken off) ; cirri of first pair of parapodia 

 (b) ; eyes and eye-stalks (c) ; between which is 

 seen the tip of the median small tentacle (d), and 

 in front the small paired tentacles . The ' ' weaving- 

 feet " (e), with bristles, and vential cirri or buccal 

 tentacles, directed across the mouth, followed by 

 other parapodia. The ventral bloodvessel (/) 

 with its broad square termination. 



