74 NORTH AMERICAN 



with a large, fairly distinct nucleolus. There extend backward from 

 this cell two finger-shaped, submedian extensions nearly as long as the cell 

 itself. Notwithstanding the distinctness of the organ and appendages the 

 position of the excretory pore remains to be discovered. The tail tapers 

 from in front of the anus in such fashion that at the beginning of the 

 final fourth it has a diameter about one-fourth as great as at the anus. 

 Thence onward the tail is cylindroid to the terminus, which bears a trun- 

 cated, conical, unarmed spinneret. The three caudal glands are minute, 

 close together, opposite to and a little behind the anus. From the slightly 

 depressed vulva the chitinized vagina leads inward at right angles to the 

 ventral surface half way across the body, where it joins the two symmetrical- 

 ly placed uteri. The reflexed ovaries reach about one-third the distance 

 back to the vulva and contain a few developing ova arranged single file. 

 The species is viviparous. Two embryos and a developing egg have been 

 seen in each uterus at the same time. The eggs are somewhat elongated, 

 about as long as the body is wide, and a little less than half as wide as they 

 are long. 



64 



.2 10. I4.(?) M 82. 



1.5 mm. 



.7 i.i 2. 2.4 1.9 



The tail of the male is like that of the female in form and size. In 

 front of the anus there is a ventral series of seven tubular, protrudable, sup- 

 plementary organs, occupying a space nearly equal to the length of the tail. 

 The hindermost is opposite the proximal ends of the spicula. Each of these 

 organs is about half as long as the body is wide, has its proximal end slightly 

 cephalated by expansion, and its distal end slightly curved. The circular 

 apertures through which the organs are protruded disturb the ventral con- 

 tour distinctly, each of them occupying a space about equal to the width of 

 four annules of the cuticle. There are no special setae or papillae either in 

 front of the anus or behind it. The two equal, uniform, slender, very 

 strongly arcuate spicula are about one and one-half times as long as the 

 anal body diameter, and their proximal ends are cephalated by expansion. 

 The proximal ends lie nearly opposite the body axis. There is a simple ac- 

 cessory piece, applied for a short distance to the distal ends of the spicula, 

 having a backward pointing process two-thirds as long as the anal body 

 diameter. 



Habitat: Potomac River, Washington, D. C. Sublimate to balsam. 



3i 



23. Aphanolaimus minor, n.sp. * .6 mm. 



8 3-3 3-9 4-7 2.6 



The moderately thin, transparent layers of the colorless, naked cuticle 

 are traversed by fine transverse striae, resolvable with moderate powers, 

 and not modified on the lateral fields. The presence of wings is indicated 

 by two lines extending from near the middle of the neck well onto the tail. 



