HABITS. 7 



gesserensis, L. sanguineus, AmpJdporus lactifloreus, Micrura purpurea, M.fasciolata, and others, as 

 well as to observe various interesting phases in their development. The vessels were always placed 

 in a cool, and, if possible, in a darkened position, in accordance with the habits of the animals in their 

 native sites ; but the sea- water was not changed more frequently than four or five times a year, and in 

 some cases not at all. Such confinement generally blanched the snout of Lineus marinus, so as to 

 render the groups of eyes visible. The pallor of the upper and under surfaces of the snout in this, 

 species is peculiar, for the other parts of the animal are not affected. It occurs chiefly in the region 

 of the cephalic sacs, across the entire breadth of the snout, and extends forward at the margins to 

 the tip ; the pigment of the centre of the snout anteriorly, both dorsally and ventrally, and the 

 reddish hue in the region of the cephalic pits remain. I have kept this species, indeed, so long that 

 the snout has become completely etiolated, with the exception of the eye-specks and the reddish 

 coloration of the cephalic fissures. Moreover, throughout an inch of the anterior part of the body, 

 the ventral surface had assumed a pale pink colour, and the six dark stripes on the dorsum were 

 separated by a ground-colour of the same pale hue, which, besides, here and there interrupted the 

 longitudinal dark bands. In the instances, again, of AmpMporus lactifloreus and the pale Tetra- 

 stemmce, the opacity of the cutaneous textures is considerably increased ; and as the two latter are 

 generally best adapted for the investigation of certain minute details, it always became necessary 

 to send to the rocks for a fresh supply. This opacity in the pale species is due to an increase 

 of yellowish colouring matter in the cutaneous cells, and the deposition of brownish-red pigment, 

 a change probably arising from a more frequent exposure to the sun's rays. In some specimens of 

 A. lactifloreus under these circumstances, a general augmentation also occurs in the reddish pig- 

 ment of the ganglia and anterior portions of the lateral nerves. A similar alteration ensues in 

 other species, such as Carinella annulata and Lineus bilineatus, the former changing from pale brick- 

 red to deep brownish red, and the latter from pale-pinkish buff to brown, thus intensifying the 

 contrast with the pure white lines present in each case. This variety of tint, from exposure or 

 seclusion, likewise occurs in their native haunts. Thus, for example, specimens of Nemertes Neesii, 

 from a chink in the Gouliot Caves of Sark, have a much paler aspect than those from an ordinary 

 tidal pool. The rule, however, has many exceptions, for in the same caves very dark olive speci- 

 mens of Lineus gesserensis are found, while a variety of a pale reddish hue lives under stones 

 beneath the open sky at the mouth of one of them. After protracted confinement without food, 

 the longer forms generally lie coiled in an intricate mass on the bottom of the vessel, or, if only 

 moderately elongated like Micrura, rest as a double band, and their bodies diminish in bulk 

 to a very great degree. Under the same conditions the smaller species, such as Tetrastemma and 

 Prosorhoclwius, are often found at the margin of the water, and some having receded too far 

 from their element become dried on the side of the jar. The latter accident especially occurs 

 amongst groups of recently captured specimens, which have not yet attained the experience 

 necessary for their preservation in this artificial habitat. Some sustain life under almost complete 

 abstinence for very long periods, such as a year or eighteen months, their bodies being apparently 

 supported by the slow absorption of their own tissues, so that, as before mentioned, their size is 

 greatly reduced. There is, indeed, no structure in the bodies of the majority that is not capable 

 of such change, and thus decrease, in every respect, is easily attained. I have not sufficient 

 facts to enable me to make generalisations on the subject of their longevity ; but the larger 

 Nemerteans, e.g. Lineus marinus, L. gesserensis, and Z. sanguineus live for several years, even 

 under very unfavourable circumstances, in confinement. With ordinary care, also, they can be 



