60 
ZOOLOGY, 
The common earth-worm (Fig. 66) is cylindrical and 
many-jointed. The small month opens on the under side 
of the first segment. The earth-worm is able to climb per- 
pendicularly up boards or the sides of buildings by minute. 
Fig. 65.— Large leech, natural size, a, a tooth; 6, head enlarged with the eyes; 
f, triradiate teeth ; V , view of the three teeth, enlarged. Gissler, del. 
short, curved bristles, which are deeply inserted in the mus- 
cular walls of the body, and arranged in two double rows 
along each side of the body (Fig. 49,9). In burrowing it 
thrusts the pharynx into the end of the head, causing it to 
