SYSTEMATIC INDEX. XXV 



ORDER I. INTESTINAL WORMS. 



I 



These are simple and naked, without limbs. 



1. Ascaris tribe Have their body long and round, tapering 

 each way; and the head with three orifices for suc- 

 tion page 299 



2. Flu.ke*worm tribe -Have their body flattened, and some- 

 what oval; and two pores, or sometimes only one ib. 



3. Tape-worm tribe. Have their body flat and jointed, and 

 the head with four orifices for suction 300 



4. Earth-woi-m tribe. Have their body cylindrical, with nu- 

 merous annules, or rings ; and furnished with minute 

 concealed prickles ib. 



5. Leech tribe. Have their body oblong, and appearing as if 

 cut off$ at each extremity. When in motion, the head 

 and tail are dilated, or spread out ib. 



ORDER II. MOLLUSCOUS WORMS. 



These are simple, but furnished with limbs. 



6. Slug tribe. Have the mouth in front, four tentacula, or 

 feelers ; and an orifice in the opening which is at the side 



of their body 301 



7. Sea-anemone tribe. Have the mouth in the upper part of 

 their body. It is capable of being extended, and is s ur- 

 rounded by tentacula, or feelers. The body is fixed. . . . 302 



8. Cuttle-fish tribe. Have the mouth in front of their body; 

 and eight or ten arms, beset with suckers ib. 



9. Star-fish tribe. Have the mouth in the centre beneath ; 

 and the body compressed, leathery, flat, generally divided 

 into several rays, and rough with tentacula 303 



ORDER III. TESTACEOUS ANIMALS. 



These animals are like those of the last order, but covered with 

 a shell. 



10. Cockle tribe. Have a two-valved shell, the hinge furnish- 



ed with two teeth, or prominences, near the beak, and a 

 larger remote one on each side, each locking into the 

 opposite valve 304 



11. Oyster tribe. Have a two-valved shell, and the hinge 



w ith a somewhat oval hollow in place of teeth ib. 



