completely absent (as for instance anmong certain Diclidophoridae). The 

 lateral pair of nerves always exists but is usually thinner and shorter than 

 the ventral. Between the trunks comnmissures can be seen as was noted 

 by Lang (Lang, 1880) for Capsala martinieri Bosc ( = Tristomum molae^ 

 auct . ) (Fig. 76). The nerves which lead from the main nerve trunks 

 usually divide into a network of nerves which interlace the entire periphery 

 of the animal. When the nervous system of monogenetic trematodes and 

 Rhabdocoela are compared, a complete coincidence of main traits is evident 

 (aside from the secondary traits which are connected with the powerful 

 development of the attaching organs among monogenetic trematodes). 



p. 52 



Fig. 73. Polystoma integerrimum 

 Froelich, diagram of tVe anterior 

 part of the nervous system of an 

 adult worm, dorsal view, (Accord- 

 ing to Andre, 1910). 



Fig. 74. Polystoma integerrimum 

 P3\j;,elich, the same diagram, lateral 

 view. (According to Andre, 1910). 



Especially interesting are two aspects --immediate separation of the a^iterior 

 nei*ves into separate fibrillae, and the weak development of the commissures 

 between the main nerve trunks within the limits of both groups. 



Organs of feeling are represented by eyes and sensitive nerve 

 endings scattered within the cuticle along the entire body, but which occur 

 in greater numbers close to the anterior edge and near the attaching organs. 

 The sensitive fibrillae described by a number of authors apparently do not 

 exist. 



It has not yet been ascertained if the special suckers located on 

 the dorsal side of a number of Capsalidae have any relation to the organs 

 of feeling. 



47 



