THE EUNICIDJE. 



231 



branchiae are intensely red. But the tints depend much on the situation where the Worm lives. 

 When they are found in clefts of rocks, living in a kind of gallery which they construct, they are 

 rich in their tints, and are iridescent. On the other hand, if they are taken amongst sea-weeds, or 

 from off a muddy bottom, they are dull in colour. 



The Sao,* one of this family, lives in a tube which it constructs for itself, and which presents 

 the exact appearance of a quill pen. It is of a horny substance, about four inches long, smooth, 

 transparent, and somewhat flexible. Living in soft mud, the animal immerses one end of this 

 tube, and protrudes the other end to some distance. The habits of this Worm have been 

 described with great accuracy by Dr. Johnston, whose words we quote : 



" One unceasing object of its life is the capture of prey. For this end it must protrude 

 the anterior portion of the body beyond its tube, and raise itself above the surface of the 

 mud, and remain in this position on watch. To enable the Worm to do this with ease is, I 

 conjecture, the office of the forceps-like bristles of the feet ; with their ends, it may hook itself 

 to the rim of the tube, and thus obtain a support without the waste of muscular power. A long 

 watch is thus rendered less irksome, while at the same time the capacity to seize upon a passing prey 

 is increased. The prey caught, analogy leads us to conclude that the Worm will instantly retreat 

 and sink within its tube, where it can feed without disturbance or fear. But as the entry and 

 passages are narrow and unyielding, it seems to follow that the prey should be held by the mouth 

 alone, when in the act of being dragged within the tube, and hence surely the reason that the mouth 

 has been furnished with the hard tubercles to the lips ; for when pulled together and put in contact, 

 they must give a firmer grip and hold than could otherwise be taken. The use of the tube is 

 to protect the body from the pressure of the soft mud in which it stands immersed. When the tube 

 is overset, or cast out by the waves or accident, the Worm leaves it, and becomes in its turn exposed 

 to enemies. To protect itself from these, while a new tube is being secreted, nature has amply 

 furnished the Sao with a series of bristling lances on each side. These ... 



arms are of exquisite make, very fine and very sharp ; and those of the 

 upper bundle have their points bent and inclined towards those of the 

 lower bundle, which are likewise bent to meet them. Arms like these 

 will inflict wounds on the tiny assailants of the Sao, sufficiently painful 

 to repulse them, and a lethal wound is not necessary." 



The Eunicidee, as a rule, undergo metamorphoses ; but a few of 

 them are born in the shape of their parents and in the viviparous 

 manner. The larvse, in the first instance, are ciliated, and there are 

 one or more special ciliated bands in particular regions of the body, 

 and assisting in locomotion. Some genera have bands at both ends, or 

 at one extremity only. The head of the perfect worm gradually develops, 

 and then the tail out of the larval form, and the ciliated bands 

 are lost. The segments between the head and tail are formed, as it 

 were, by a budding. 



The family Nereidse have long slender bodies with two anal cirri, 

 and the head is flat and four-eyed. There are two small middle and 

 two large outer feelers at each side of the mouth. The pharnyx is 

 protrusible, and there are two large horizontally-moving jaws armed 

 with denticles. The parapodia are double, and have sharp spines, 

 but no hair-like bristles. The genus Nereis is very common, and nearly 

 every stone that is turned over near the sea-water edge sets some 

 moving. Gosse describes the Pearly Nereisf a common species, as having 

 a warm brown-coloured upper surface, but the beautiful flashes of 

 iridescent blue that play on it in the changing light, and the exquisite 

 pearly opalescence of the delicate pink beneath, are so conspicuous as to 

 have secured it the title of pearly. The great dorsal vessel is a dark red line along the back Nereis 

 pelagica is another species, which attains six inches in length, and is as thick as a quill The body 



Northia tubicola. f Nereis maryaritacea. 



NERVOUS SYSTEM OF NEREIS 

 (After Gegenbaur). 



, upper, 6. inferior gangiion of 

 plinvynx: c, ventral trunk; d, nerves 

 of mouth, e, of antennae: /, eyes 

 placed on superior ganglion of oeso- 

 phagus. 



