back, with protrusible tubular pharynx. AUmentary canal simple 

 or much branched. Chiefly aquatic (marine and fresh-water) ; 

 some terrestrial, living in damp places, generally under logs or 

 stones. 



(2) Trematoda {e.g. Fasciola hepatica, the well-known Liver- 

 fluke of the Sheep. — See Fig. 3). Internal or external parasites ; 

 usually of oval shape. Unsegmented. With suckers and some- 

 times horny hooks for attachment to host. Alimentary canal 

 bifurcate, sometimes branched. 



(3) Cestoda [c.ij. Tcenia of various species, parasitic in man, 

 dog, etc. — See Figs. 1 and 2). 



Elongate parasitic creatures, of ril)l)on-like form, witli a 

 rounded " head " bearing suckers or hooks and suckers, followed by 



a series of segments increasing in size 

 posteriorly. The hinder segments are 

 generally full of eggs. The larval or 

 young forms (see Fig. 4) of these 

 worms are found as bladder-like 

 " cysts " of various sizes embedded in 

 the organs [cfj. the liver) of some 

 animal which is liable to be eaten by 

 their final host. Alimentary canal 

 absent in all stages. 



\_Notc. — In collecting Tapeworms 

 great care must be taken to find the 

 head (Figs. 1 and 2), which is very 

 minute and easily broken off, as it 

 may be attached firmly to the host's 

 tissues. (See p. 2.)] 



B. NEMERTINEA (see Fig. 15). 

 (Such as Linens of the sea-shore.) 

 Generally very elongate, unsegmented, 

 more or less flattened worms, capable 

 of great extension and contraction. 

 Sometimes several yards in length 

 when extended. Possessing a remark- 

 able protrusible proboscis, in a sheath 

 lying above the alimentary canal. 

 Mostly marine, rarely on land or in 

 stones, etc. 



Figure 4. 

 A " Bladder - worm,' Ci/sticerciis 

 temiicoUU, enlarged about \i 

 diameters. This is the larval 

 stage ol' one ot the common 

 Tapeworms of the Dog. and is 

 found in the lining of tlie body- 

 cavities of Sheep, Cattle, ete. 



[Cestoda.] 



fresh water, living under 



C. NEMATODA (see Fig. 5). (Such as Amtris lumhricoidcs, 

 the largest round- worm found in man.) 



Mostly parasitic worms of elongated form, with flexible but not 

 extensible cylindrical, unsegmented body. (There are many free- 

 living Nematodes, l)ut these are mostly very minute, living in 



