FREE-LIVING FRESH-WATER NEMATODES 8l 



lower layers with high powers. There are short hairs to be found here 

 and there on the surface of the body, more particularly toward the ex- 

 tremities. The conoid neck ends in a somewhat rounded head not set 

 off by any constriction. The cephalic setae appear to be ten in number 

 (eight submedian and two lateral), outward pointing, each about one- 

 sixth as long as the head is wide, and placed on the outer margin of the 

 front of the head opposite the posterior portion of the pharynx. The 

 members of the submedian pairs are, however, of unequal size. There 

 are six small, pointed lips surrounding the mouth opening. It is cer- 

 tain that these lips bear papillae, but the number is not known. Lat- 

 eral organs in the form of somewhat stirrup shaped markings one- 

 fourth as broad as the corresponding portion of the head, occur at a 

 short distance behind the base of the rudimentary pharyngeal cavity. 

 This latter is a more or less triquetrous cyathiform cavity having its 

 walls distinctly chitinized and bearing at its base one or more protuber- 

 ances near the point where the lumen of the oesophagus begins. One 

 of these is a ridge, the others minute teeth. The average width of the 

 main pharyngeal cavity is about one-third that of the head. The oeso- 

 phagus is slightly expanded to receive the pharynx, but otherwise be- 

 gins as a tube about three-fifths as wide as the anterior part of the 

 neck, and expands very gradually to the end, where it is a little more 

 than half as wide as the base of the neck. The lining of the oeso- 

 phagus is a distinct feature throughout its length. There is a distinct 

 rounded cardia. The intestine, which becomes at once about two-fifths 

 as wide as the body, is separated from the oesophagus by a distinct 

 constriction, in which lie the three granular bodies whose presence 

 gave origin to the name of the genus. The intestine is relatively thick 

 walled, its small cells containing scattered granules of small size, which 

 are not arranged in any very definite manner. The intestine frequently 

 contains diatoms in large numbers, thus indicating that these are a 

 common source of nourishment for this species. From the slightly de- 

 pressed anus the rectum, which is about as long as the anal body 

 diameter, extends inward and forward to join the intestine, which is 

 narrowed at its extremity so as to be about two-fifths as wide as the 

 body. Nothing is known concerning the ventral gland. The longi- 

 tudinal fields are distinctly developed, being about one-fourth as wide 

 as the worm itself. The nerve-ring surrounds the oesophagus some- 

 what obliquely. The tail is conoid in the anterior third in such fashion 

 that at the beginning of the middle third it has a diameter about one- 

 fourth as great as at the anus. Thence onward it tapers gradually to 

 the slightly swollen spinneret or outlet for the caudal glands. These 

 latter, three in number, are located tandem in the tail opposite to and 

 slightly behind the anus. From the slightly elevated vulva the vagina 

 leads inward at right angles to the ventral surface fully half way 

 across the body. The vagina is bifurcated and extends in opposite di- 



