LEECHES, EARTH AND SEA WORMS. 



47 



to them. are the Nemertian worms, acorn-tongue, and star- 

 worms, that form Classes VI, VII, and VIII. 



NOTE. Lingulae, quite similar to those of 

 to-day, are found in the Trenton limestone ; 

 2,090 species are known, of which 2,000 are 

 extinct. 



ce- 



Class IX. LEECHES, EARTH AND 

 SEA-WORMS (Annulata). 



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. 

 The eggs are laid in sacs 

 in the fish-leech, Clepsine, 

 and when hatched the 

 young cling to the mother; ethers 

 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 



5 



b~< 



FIG. 48. Section of a 

 leech. a, anterior 

 sucker ; , posterior 

 sucker ; c, anus ; d^ 

 d, d, stomach ; ce, 

 oesophagus ; z, intes- 

 tine : j, s, glands of 

 the skin. 



