- S. 448) 



THE MONONCHS 



FIG. 14. Female M. tri- 

 churus. This mononch 

 has only one ovary. The 

 tail is very long and slen- 

 der and quite likely is 

 more or less prehensile. 



1* 



Nerve Commissures. A constriction in the intestine is sometimes ob- 

 served at a point not far in front of the rectum, say at a distance equaling 

 3 to 5 body diameters. This constriction is sometimes so pronounced as 

 to cause the posterior portion of the intestine to simulate the pre-rectum 

 of Dorylaimus. There is here, however, no true pre-rectum. The con- 

 striction seems to be caused by mural commissures surrounding the 

 intestine. The writer can 

 only suggest the possibility 

 of the existence of special 

 nerves at this point, which 

 leave the ventral field, pass 

 slightly backward, then al- 

 most immediately become 

 squarely transverse, encir- 

 cling the intestine until they 

 are very near the dorsal 

 field, where they turn sud- 

 denly backward. 



Amphids 



If is almost certain that 

 small amphids occur on all 

 mononchs ; the writ- 

 er found them pres- 

 ent on three-fourths 

 of the known spec- 

 ies. As their gen- 

 eral characters have 

 never been adequate- 

 ly described, their 

 form and position 

 are specially noted 

 here, as well as more 

 explicitly in the var- 

 ious illustrations. 

 The external indica- 

 tions of the amphid 

 are always located 



GO the lateral lines somewhere between the base of the lips and a poin* 

 opposite the middle of the pharynx. The periphery, which in some .cases 

 may be unclosed behind, is usually more or less elongated or elliptical in 

 form, its long axis lying transversely on the head. These amphids are 

 seldom more than one-sixth as long as the head is wide, and are usually 



ttflal 

 X450 



