398 



ANNELIDES. 



120 or more rings ; the bulge is towards its anterior third. Under the sixteenth ring are two pores, of which the 

 use is unknown. It pierces the ground in all directions, perforating it remarkably well, and subsists on roots, 

 woody fibres, animal matter, &c. In the month of June it searches at night above ground for a mate. 



[It is especially in rich and well-manured soils that the Earthworm delights, particularly in gardens 

 and meadows ; they are extremely sensitive to movements of the earth ; and anglers, knowing well their temerity 

 in this respect, take advantage of it, in order to obtain a supply of these animals for baits, by introducing a spade 

 or fork into the ground, and stirring the soil, when they soon appear on the surface. We are indebted to Charles 

 Darwin, Esq., for a remarkable and interesting memoir on the utility of this animal, read before the Geological 

 Society. The worm casts, which so much annoy the gardener by deforming his smooth-shaven lawns, are of no 

 small importance to the agriculturist ; and this despised creature is not only of great service in loosening the 

 earth, and rendering it permeable by air and water, but is also a most active and powerful agent in adding to the 

 depth of the soil, and in covering comparatively barren tracts with a superficial layer of wholesome mould. The 

 author's attention was directed by Mr. Wedgwood, of Maer Hall, Staffordshire, to several fields, some of which 

 had a few years before been covered with lime, and others with burnt marl and cinders, which substances in every 

 case are now buried to the depth of some inches below the turf, just as if, as the farmers believe, the particles had 

 worked themselves down. After shewing the impossibility of this supposed operation, the author affirms that 

 the whole is due to the digestive process by which the common Earthworm is supported, since, on carefully 

 examining between the blades of grass in the fields above-mentioned, he found that there was scarcely a space of 

 two inches square without a little heap of the cylindrical castings of worms ; it being well known that worms 

 swallow earthy matter, and that having separated the serviceable portion, they eject at the mouth of their burrows 

 the remainder in little intestine-shaped heaps. Still more recently Mr. Darwin has noticed a more remarkable 

 instance of this kind, in which, in the course of eighty years, the Earthworms had covered a field then manured 

 with marl, with a bed of earth, averaging thirteer inches in thickness.] 

 [Fig. 206, 6, represents the anterior extremity of the Earthworm, to show the mouth, as well as the setae directed 

 backwards upon the segments of the body, by means of which it is admirably enabled 

 to work its way through the earth, their backward direction enabling it to retain its 

 station as it protrudes its head further into the earth. Fig. c, represents one of its 

 eggs, inclosing, as is sometimes the case, two young ; and fig. d represents the escape 

 of the young worm from the egg, the anterior extremity of which is furnished with 

 a peculiar valve-like structure ; these two figures are highly magnified.] 



Hypogaon, Sav., have an additional single, or uneven, bristle upon the back of 

 each ring. They are only known in America. 



MM. Audouin and M. Edwards likewise distinguish the Trophoni its, which has 

 four bundles of short silky bristles on each ring, and at the anterior extremity a 

 great number of long and brilliant bristles, encircling the mouth. 



The Naides (Nais, Linn.), — 

 Have the elongated body and the rings less marked than in the Earthworms. 

 They live in holes which they perforate in mud at the bottom of water, 

 and from which they protrude the anterior portion of the body, incessantly 

 moving it. Some have black points upon the head, which have been 

 regarded as eyes. They are small worms, the reproductive power of which 

 is as astonishing as that of the Hydra or Polypus. Many species exist in our 



fresh waters. 



Some have very long bristles ; others (the Stylaria, Lamarck) a long protrusile 

 trunk ; several (Proto, Oken) have small tentacles at the hind extremity, and there 

 are others with very short bristles. 



To this genus may be approximated certain Annelides allied to the Earth- 

 worms, which fabricate the tubes of clay, or debris, into which they retire. 

 Such are the Tubi/ex of Lamarck, which, however, requires further examination. 



Climene, Sav., — 

 Appears likewise to belong to this family. Their body is rather thick, 

 with few rings, and bears, for the greater portion of its length, a range of 

 strong bristles, and, a little higher up, a bundle of finer bristles on the dorsal aspect. The head has 

 neither tentacles nor appendages ; posterior extremity truncated and rayed, and they also inhabit tubes. 



Fig. 206. — Lumbricus terrestris. 



THE SECOND FAMILY OF THE ABRANCHIOUS ANNELIDES,— or, 

 The Abranchia without Bristles, — 

 Comprise two great genera, both of which are aquatic. 



