MICRURA FASCIOLATA. 199 



wrinkles of the body. The pale portion at the tip of the snout, and especially its margins, are 

 increased in breadth ; the latter, indeed, being continuous with a pale lateral border (not due to 

 the cilia) throughout the entire length of the animal. The under surface in such examples is of a 

 dull whitish hue, with the exception of the reddish ganglionic region. A dull olive variety of 

 large size (six to ten inches) also occurs in the recesses of the tangle-roots in the Shetland 

 Islands. Some of the examples with white bands have also a whitish ventral surface; and occa- 

 sionally the bands, even when present, are very inconspicuous. 



Head. — Somewhat spathulate, flattened, tapered towards the front, which is rounded and 

 furnished with a central papilla, wider than the rest of the body. There is a deep lateral fissure 

 on each side, with a reddish coloration posteriorly. Just within the pale margin of the snout are 

 numerous eyes, those in front being best seen from the dorsum, especially in pale specimens, and 

 also from the cephalic fissures. They form a single converging row on each side, to the number 

 of eight or twelve. Young specimens are famished with two conspicuous eyes only. The mouth 

 occupies the usual position behind the ganglia. 



This is one of the most beautiful Nemerteans, from the striking contrast in its colours 

 and the soft and velvety aspect of its skin. It is evidently a dweller in crevices, and has a 

 great tendency to hide under debris or other shelter in glass vessels ; and if this protection be 

 denied it, the animal frequently coils itself in a mass, either with or without enveloping mucus. 

 Some are hardy in confinement and live for years, others are irritable and fragile, breaking 

 themselves on the slightest interference into many fragments, the separation almost always occur- 

 ring at the white belts. This rupture often takes place before they are removed from the 

 collecting-bottle, especially if they do not have it all to themselves. Fragments of the posterior 

 end of the body turn slowly in the vessel, and live a long time. Of the two well-marked 

 varieties, viz., the banded and the uniformly tinted, the latter are the less fragile, and their bodies 

 are more flattened. The styliform process at the tail can be elongated to an extreme degree. 

 The skin presents an acid reaction. 



The spermatozoa are fully developed in the beginning of November, causing pale trans- 

 verse bars at the sides of the males. The same elements are fairly matured in Zetlandic examples 

 in August. 



It is doubtful whether the Fasciola caudata of 0. F. Miiller has any connection with this 

 species, especially as it was found by 0. Fabricius gregariously associated amongst litoral fuci on 

 the shores of Greenland. The same author's Fasciola fiaccida has closer resemblances both in 

 description and figure ; though, as regards the transverse white lines, it is to be remembered that 

 he gives the same account of F. viridis. His figure and the remark concerning the fragility of the 

 species show a close affinity. The Flanaria Jilaris of this author, again, may be regarded as 

 a young specimen, though he represents the tail too elongated. He found it on Madrepora 

 jprolifera. Montagu observes that the colour of his specimens {Flanaria lineata, Mont. MS.) was 

 " rufous brown, with about ten white lines across the back. Beneath pale, without the lines." The 

 Flanaria rvfa of the same naturalist (MS., p. 232) is either a uniformly tinted example of this 

 species, or a variety of Lineus gesserensis. It was found on a large oyster. Ehrenberg gave a 

 good description and figure of the animal from specimens found in the Adriatic. He mentions 

 the presence of five eyes on each side, and that the ovarian aperture (mouth) lies under the second 

 dorsal white bar. He also alludes to the copious exudation of mucus with which it forms a 

 sheath. I have followed J. Miiller in including the young form, Fylidiwn gyrans, under this 



