FREE-LIVING FRESH-WATER NEMATODES 65 



diameter. The three caudal glands are located in the anterior third of 

 the tail. The lateral fields vary in width in different parts of the body. 

 A little in front of the anus they are about two-fifths as wide as the corre- 

 sponding portion of the body, and contain rather numerous scattered nuclei 

 of such a size that about eight would be required to reach across the field. 

 Farther forward the field is narrower, about one-fourth as wide as the 

 middle of the body. Anteriorly it is wider, about one-third as wide as the 

 base of the neck. Nothing is known concerning the renette. The nerve- 

 ring surrounds the oesophagus somewhat obliquely a little in front of the 

 middle of the neck. From the elevated and rather large and conspicuous 

 vulva the vagina leads inward at right angles nearly half way across the 

 body, where it joins the single uterus, which extends forward, and is of 

 such a size as to contain apparently but one egg at a time. The ovary, which 

 at first is three-fourths as wide as the body, extends forward and tapers 

 gradually, so that at the blind end, considerably in front of the cardia and 

 a short distance behind the nerve-ring, it is one-fourth as wide as the corre- 

 sponding portion of the body. It sometimes happens that the blind end of 

 the ovary is disposed in a single coil. The rather thick shelled eggs are as 

 long as the body is wide, and about three-fourths as wide as long, and appear 

 to be deposited before segmentation begins. The small spermatozoa found in 

 the uterus are of such a size that at least ten placed side by side would be 

 required to span the diameter of one of the eggs. There is a very small, 

 posterior rudimentary branch to the uterus, which extends backward from 

 the vulva a distance about equal to two-thirds the radius of the body. 

 Around the vulva are four distinct, unicellular vaginal glands. 



7i- 

 .7 9.4 22. -M- 87. 



1.5 mm. 



1.6 2.9 3.5 4-2 3-3 

 The tail of the male resembles that of the female in form and size. 

 As in the females, the three caudal glands are found in the anterior third 

 of the tail, and do not extend materially farther forward than the anus. 

 The two equal, L-shaped, slender, slightly tapering brownish spicula are a 

 little longer than the anal body diameter. The anterior three-fifths lie nearly 

 parallel to the body axis, while the posterior two-fifths are arranged nearly 

 at right angles to the body axis. The distal extremities of the spicula are 

 slightly widened. At their widest part, namely near the proximal ends, the 

 spicula are about one-eighth as wide as the corresponding portion of the 

 body. They are very slightly narrower distally than proximally, where they 

 are barely cephalated by expansion. The accessory piece is not strongly 

 developed. The main portion of it lies parallel to the distal two-fifths of the 

 spicula, and is connected with the dorsal surface of the body by means of 

 muscles. The ejaculatory duct is one-half as wide as the corresponding 

 portion of the body. There are two outstretched testes. The blind end of 

 the anterior testis is located a short ' distance behind the nerve-ring, while 

 the blind end of the posterior testis is located about as far in front of the 



