NEMERTES NEESII. 179 



specks. Towards the tail the colour again becomes paler, and the dorsal specks more numerous. 

 The entire under surface is pale pinkish -white, or skin-coloured. In the darker specimens 

 the streaks are less numerous, though more boldly marked. Some examples are of a very 

 pale brownish hue, the dorsum having only pale brown pigment-grains and no streaks. Other 

 varieties, again, are very curiously mottled, like polished rosewood or walnut, or of a faint 

 yellow, speckled with brown. Young specimens from deep water are occasionally almost white, 

 or faint skin-colour, and some have a uniform dull orange hue, from the digestive chamber. 

 The proboscis in the latter examples is pale pink. Young specimens, and those from dark 

 recesses, are generally pale. 



Head. — Spathulate, wider than the rest of the body, with a pale margin, and a central streak 

 from the notch or dimple in front backwards. Eyes numerous, arranged in two dense clusters on 

 each side — a little behind the tip of the snout. Unless in pale specimens, they are distinguished 

 with difficulty on account of the dark coloration of the dorsum. They are larger than the eye- 

 specks of N. gracilis. 



Cephalic furrows. — The snout is bounded posteriorly by two dorsal transverse grooves, 

 which also mark a slight constriction. On the under surface two furrows slant outwards and 

 backwards from the mouth, a short distance behind the tip of the snout, and from these 

 the openings of the cephalic pits proceed. They are visible as two curved lines, which do not 

 reach the lateral margin of the body, and thus are wholly ventral. 



N. Neesiiis rather plentifully distributed on our coasts, four or five being occasionally pro- 

 cured under one stone, or in a fissure of the shelving rocks. The facility with which it coils and 

 twists its body in all directions is most interesting. Sometimes the posterior part of the animal 

 lies in a tangled knot, while the anterior extends outwards as a long screw, the alternate dark and 

 light shades of the dorsal and ventral surfaces forming a very agreeable contrast ; and from the 

 frequency with which it assumes this attractive position one might be excused in attributing 

 to the animal some sense of the splendour with which nature has endowed it. It floats 

 with ease on the surface of the water, the body being thrown into various undulations, as when 

 progressing on the surface of the ground, though, of course, more slowly and less distinctly. It 

 is killed by immersion in fresh water, the body before death being surrounded by a tough 

 coating of mucus, like many of its allies and the Dorides. The skin is alkaline to test- 

 paper. 



In one specimen of a pale brick-red hue, from Guernsey, the muscular investment of the basal 

 apparatus of the central stylet was abnormal (a state that could scarcely have resulted from dege- 

 neration, for it was examined on the third day after capture), being elongated posteriorly and 

 split into processes like rootlets, from the peculiarities of the fibres. 



It spawns in March and April. 



The Linens maculosus of Montagu (MS., p. 274) can scarcely refer to any other British 

 form than the above. It is described as "rufous-brown, mottled, beneath white, resembling 

 L. marinus. Length more than a foot, and not larger than Gordius aquaticus." Dr. Johnston, 

 however, first published an account of the species, from a specimen coiled in a valve of Saxicava 

 rugosa, from deep water in Berwick Bay. The Amphiporus Neesii of (Ersted, as R. Leuckart 

 mentions, is clearly synonymous with the Gordius fuscus of Dalyell (the present species), and as 

 GErsted's specific title is free from the objections connected with Johnston's, it has been chosen. 

 Sir J. Dalyell noticed its tendency to coil in knots. His examples spawned in April, the ova 



