Dr. Johnston on the British Nereides. 231 



cles, having a rather small spine in the middle of each : anal 

 segment truncate and terminated with two long styles similar 

 to the tentacular cirri. 



This little worm is occasionally met with in Berwick Bay, 

 lurking amid the roots of Confervcz, corallines, and sponges. 

 It advances through the water with considerable velocity and 

 in a wriggling manner, pushing out and alternately withdraw- 

 ing the bristles of its feet, and moving its long cirri in every 

 direction. When the creature is active and first taken, the 

 cirri have a somewhat moniliform appearance under the micro- 

 scope, but as its energy declines this appearance becomes 

 fainter ; they then appear jointed like a common Conferva, and 

 after death even these joints fade away and the whole organ 

 assumes a homogeneous structure. 



Plate VII. fig. 4. Ps.fusca, magnified. The line expresses the length of 

 the specimen. 



4. Ioida*, Johnston. 



Char. Body linear-elongate : head small : eyes two, large : 

 antenna three, cranial, filiform, submoniliform: tentacular 



cirri none : proboscis ? segments numerous : feet 



undivided, each with a dorsal moniliform cirrus and two bun- 

 dles of bristles, cue of which is very long : branchiae none : 



styles ? 



Obs. This new genus is allied to Scyllis, from which it dif- 

 fers in the number of eyes, in the absence of tentacular cirri, 

 and in the appendages to the feet, — the Scyllis having two 

 cirri to each and a single bundle of bristles, — while the Ioida 

 has one cirrus and two bundles of bristles. 



1. /. macrophthalma. Plate VII. fig. 5. 

 Hub. Amongst corallines in deep water. Coast of Berwickshire. 



Desc. Worm about an inch long and a line in breadth, of 

 a dark blue or purple colour, unspotted, linear-elongate, de- 

 pressed, smooth. Head small but very distinct, pale, rounded 

 in front, entire : eyes two, very large, lateral and nearly mar- 



* From 'loeilvs, blue or violet-coloured. The name is given by Drayton 

 to one of his Naiades : — 



11 Ioida, which preserves the azure violets." 



Polyolbicm, song 20. 



