168 ZOOLOGY. 
etc., as well as over the ground, by minute, short, curved 
sete or bristles, which are deeply inserted in the muscular 
walls of the body, and arranged in four rows along each side 
of the body. The alimentary canal is straight, the stomach V 
has three pairs of small lateral blind sacs (cceca), and the 
intestine, which is externally tubular, contains a thick inter- 
nal sac-like fold called a ¢yphilosole. 
The segmental organs are highly convoluted tubes, a pair 
to each segment of the body, except a few near the head, 
and opening internally with ciliated funnels and externally 
in minute pores situated along the under side of the body. 
The earth-worm is moneecious (hermaphroditic). 
The oviducts open in the fourteenth segment, and the 
seminal ducts (vasa deferentia) in the fifteenth. Between 
the ninth and tenth, and the tenth and eleventh segments 
are the four openings of the seminal receptacles (receptacula 
seminis). Pairing is reciprocal (see Fig. 115), each worm 
fertilizing the eggs of the other; they pair from April to July 
in the night-time. The eggs of the European Lumbricus 
rubellus Grube are laid. 
in dung, a single egg in 
a capsule; L. agricola , 
lays numerous egg-cap-, 
sules, each containing 
sometimes as many as: 
fifty eggs, though only 
three or four live to de- 
velop. The development 
of the earth-worm is like 
that of the leech, the 
germ passing through a. 
; a w= morula, blastula, gas- 
ger Gnesin) evan ater Me cemtalan ot trula and neurula stage, 
d Ik ; 0, embryo further advanced ; 0, mouth; 
ee ‘il older; , primitive streak; a the worm, when hatch- 
neurula ; 0, its mouth.—After Kowalevsky. ing, resembling the pa- 
rent, except that the body is shorter and with a much less. 
number of segments. 
While the earth-worms are in the main beneficial, from 
their habit of boring in the soil of gardens and ploughed 
