LEECHES, EARTH AND SEA WORMS. 47 
to them are the Nemertian worms, acorn-tongue, and star- 
worms, that form Classes VI, VII, and VIII. 
NotTEe.—Lingulz, quite similar to those of 
to-day, are found in the Trenton limestone; 
2,090 species are known, of which 2,000 are 
extinct. 
Class [X.—LEECHES, EARTH AND 
SEA-WoRMS (Aznulata). 
The leech (Fig. 48) is a common 
form of the higher worms. The body. 
is flat and divided by numerous seg- 
ments ; the head small, with ten small 
and simple eyes; the mouth bears 
three teeth, arranged so that the 
wounds they inflict ap- 
pear as gashes radiating 
from the center. Some 
swim readily, while oth- 
ers move by the use of 
their suckers, that are 
one or two in number. Fic. 49.— 
The eggs are laid in sacs ce 
in the fish-leech, Clepsine, _Jeech. 
and when hatched the 
young cling to the mother; others 
are laid in small oval sacs (Fig. 49), 
and deposited upon the stems and 
leaves of water-plants. 
Note.—Land-leeches are greatly dreaded 
in the forests of India (Fig. 50), and in the 
East India islands they exist in such vast 
numbers that Semper, the naturalist, was 
driven from the woods at Luzon by-them, the 
animals falling upon him like dew from the 
Fic. 48.—Section of a 
leech. @, anterior 
sucker ; 4, posterior 
sucker; ¢, anus; @, 
d, d, stomach; @, 
cesophagus ; 7, intes- 
tine; s,s, glands of 
the skin. 
