It is curious that among certain forms (for instance Diclybothriidae) one 

 observes more powerful development of the dorsal musculature, whereas 

 among the majority of monogenetic trematodes the musculature of the 

 ventral side is the most powerfully developed. Parenchymatose muscular 



fibers are chiefly located in the 

 main portion of the body in more 

 or less well-developed dorso- 

 ventral bunches. Less frequently, 

 one encounters fibers which stretch 

 longitudinally as in Cestoidea. 

 Such disposition of the fibers is 

 usually observed in the anterior 

 or posterior ends of the body. 



Fig. 58. Capsaloides sp. , propodia of 

 the adult worm from Tetrapturus sp. 



Parenchyma. Parenchyma 

 fills the entire body between the 

 dermal muscular sac and the in- 

 ternal organs and has the appear- 

 ance of polygonal cells, or more 

 seldom syncytial tissues with 

 numerous interior gaps between 

 the cells which are filled with a 

 from the region of Woods Hole (Atlantic colorless fluid. The latter is de- 

 Ocean), void of formed elements. Often 



parenchyma has a fibrillar 

 structure; sometimes it is differentiated, it is true to a small degree, into 

 ecto- and endoparenchyma as occurs in Cestoidea. As Goto indicates, 

 parenchyma divides very sharply into ectoparenchyma and endoparenchyma 

 in Heteraxine heterocerca Goto. At the same time, he even notes the pre- 

 sence of a special membrane which lies between these layers (Fig. 60). 



Digestive System. The digestive system for the most part is 

 very strongly developed among monogenetic trematodes. It is represented 

 by a pharyngeal apparatus, esophagus and intestine. 



45 



The buccal aperture is located subterminally and less often 

 terminally. Around the buccal aperture one can sometimes observe lip 

 like growths, more often, however, its edge is 

 smooth. The buccal aperture usually leads 

 into the buccal funnel which is often surrounded 

 by a more or less isolated sucker, or on the 

 interior edges of the funnel there can be, as 

 has been mentioned above, two suckers 

 developed in varying degrees. All these 

 formations serve for the attachment of the 

 anterior end of the worm's body during 

 feeding. Posterior to the buccal funnel 

 lies a more or less well-developed buccal 



Fig. 59. Diplectanum 

 aequans Wagener, diagram 



of the cross section of the 

 ventral coverings. (According 

 to Maclaren 1903) 



39 



