386 



LUMBRICONEREIS GRACILIS. 



Ranges to the Mediterranean, Adriatic (Ehlers), Madeira (Langerhans), and to 

 Norway. 



Dredged in the e Porcupine ' Expedition of 1870 in eighty-one fathoms off Cape 

 Finisterre. 



Head (Plate LXII, fig. 4) forms a blunt cone, sometimes in lateral view almost ovoid, 

 as Ehlers says. A median dorsal process with backward curve on each side occurs 

 posteriorly. 



Body small, elongated, and beautifully iridescent, tapering posteriorly to a slender 

 tail, which in the only example of the region was devoid of cirri. Ehlers had also only 

 incomplete examples. Few of the specimens had the bristles in a satisfactory condition, 

 probably from friction in the net of fine gauze inside the dredge. 



Proboscis. — The dental apparatus (Plate LXII, fig. 4 a) has, superiorly, a pair of 

 curved maxillae which are articulated posteriorly to a process which has a short anterior 

 region and a larger tapered posterior part as in L. ting ens. Each of the great dental plates 



Fig. 80. — Transverse section of Lumbriconereis gracilis. 



has four strong teeth. The anterior or antero-lateral plates are two in number on each 

 side and appear to have only one tooth in each, but as the posterior on one side has a broad 

 edge, this, as Ehlers states, may often be double ; indeed, this is well seen in one from 

 Lochmaddy. As in allied forms their surface is granular. 



The mandibles are anchylosed in front, but the edge has a V-shaped fissure, beyond 

 which on each side the tooth presents a double crescent, viz., an inner and a larger outer. 

 The external edge has a pigmented shelf or process. 



The body- wall is typical in transverse section. The pedicle of the nerve-cords is short 

 and the neural canal of large size. It is placed superiorly at the ganglia, but passes down- 

 ward between the cords in the intervals. The ganglia are surrounded by a zone of deeply 

 stained cells, which often form a mass inferiorly. The oblique muscles are fixed to the 

 upper and outer borders of the investment of the neural canal. 



The first foot has a small triangular posterior lobe, and a series (four) of pale spines. 

 It bears tapering winged bristles and also jointed hooks, which in this and the second foot 

 have a short terminal piece with a crown of small hooks and two wings, the adjacent end 

 of the shaft likewise having two wings. The second foot has five spines. 



