The transverse section of the body (Fig. 10) varies from a 

 rounded shape (as for instance in a series of sections of Dactylogyrus) to 

 one which is greatly flattened dorsoventrally (among representatives of 

 the genus Nitzschia or Capsala). The ventral side of the body is usually 

 slightly c-incave, and the dorsal correspondingly convex. 



a.iMn 



Fig. 5. Dactylogyrus vastator Nybelin, 

 adult worms from the gills of Cyprinus 

 carpio L. from Fd.^pshansk Ponds 

 (Leningrad region) (According to 

 Bychowsky, 1933). 



Fig. 



Vallisia striata Perugia 



and Parona, adult asymnietrical 

 worm. Natural size 10 mm. 

 (According to Monticelli, 1912). 



The lateral sides of the body are entire or smooth with few 

 exceptions (see page 43 ). This smooth-margined condition does not pertain 

 to the adhesive disc the sides of which can form an intricately cut figure. 

 The orientation of the body of monogenetic trematodes does not offer any 

 difficulty; their oral opening is, as a rule, terminally or subterminally 

 located and the attachment apparatus is always at the posterior end. 



