BY S. J. JOHNSTON. 113 



which may be divided into two groups, one group springing from 

 the ventral wall of the cup, the other from the dorsal wall of the 

 cup. The group of processes from the dorsal wall is in the form 

 of the hollow plug characteristic of the genus, with a swollen 

 dorsal ("inner wall" of Brandes) and a ventral lamellar wall. 

 The dorsal cushion-like part is divided by a longitudinal groove 

 into two main masses : its base of attachment to the ventral 

 body-wall of the worm extends along for a considerable distance, 

 but anteriorly each mass ends in a free tongue capable of being- 

 bent backwards towards the bottom of the cup. The lamellar wall 

 of this hollow clinging plug is produced in front into a very long 

 process which in the case of all the worms examined (a large 

 number) extends beyond the cup cavity for a considerable dis-^ 

 tance. The edges of the extruded part are beset with a number 

 of fine digitate processes or papillae, which contain strong muscular 

 fibres. These processes, and indeed the whole ventral lamellar 

 wall of the plug, are hollowed out into a number of well defined 

 canals, opening mostly at the ends of the processes and extending 

 to the posterior extremity of the ventral wall of the plug, at the 

 bottom of the cup. These canals are mostly filled with birds' 

 red blood corpuscles, some of which are beginning to disintegrate, 

 but precisely what becomes of these birds' corpuscles must be 

 further looked into. The group of processes springing from 

 the ventral wall of the cup consists of a single median 

 lamellar lobe, arising near the anterior edge of the cup and 

 with only a small area of attachment to the wall and a 

 free edge directed backwards (PL vii., fig. 4^r.) : behind this 

 lies a pair of lamellse attached at their anterior ends but 

 free along their lateral edges and posterior ends, which ends 

 are also directed backwards towards the bottom of the cup : 

 these two lamellae are fused together for a short distance about 

 their middle, so that together they are H-shaped. Behind this 

 again, and also springing from the ventral wall of the cup, is 

 another lamellous plate attached along its sides and posterior 

 edge to the cup-wall, but with its anterior edge free and directed, 

 forwards towards the opening of the cup. 

 8 



