water or in the soil ; some are also para- 

 sites of plants.) Tail of male nearly always 

 curved downwards, and provided either 

 with a memhranous expansion, or with 

 curved horny spicules, or both. 



D. NEMATOMORPHA (Gordiacea) 

 (see Fig. 13). Extremely long, thin, 

 wiry-looking worms, traditionally compared 

 to " animated horse-hairs." Parasitic at 

 first in the body-cavity of Insects ; after- 

 wards emerging from them to lead a free 

 life, usually in fresh water. 



E. ACAN- 

 THOCEPHALA 



[Ecliinorhynchns , 

 etc.— See Fig. 6). 

 Unsegmented, 

 cylindrical 

 worms, more or 

 less resembling 

 Nematodes, but 

 having a pro- 

 boscis armed 

 with many hooks 

 (see Fig. 7), with 

 which they attach 

 themselves to the 

 tissues of the 

 host — usually to 

 the lining of the 

 stomach or intes- 

 tines. Larvae in 

 cysts, usually in 



aquatic insects or Crustacea, sometimes in 

 fishes, preyed i;pon by the final host. 

 Alimentary canal absent. 



F. CH^^TOPODA. Body divided into 

 a number of " rings " or 

 segments, each of which 

 is provided with certain 

 groups or rows of 

 bristles. 



(1) OLIGOCH.ETA 



(Earthworms, &c.). 



Figure 6. 

 Gigantorhfnichus gigas, natural 

 size, of the Pig. This is a male 

 specimen, the female being 

 considerably larger. [ACAN- 



THOCEPHALA.] 



The large Nematode, 

 Ascarig megalocephala, 

 natural size, of the 

 intestines of the Horse. 

 This specimen shows the 

 curvature of the tail, 

 charai'teristic of tlie male 

 sex of nianv Nematodes. 

 IN'eji"atod.\.] 



Figure n. 



