52 NORTH AMERICAN 



The oesophagus begins at the lip region as a tube two-thirds as wide as the 

 head, and expands gradually and rather regularly to the end, where it has 

 a diameter three-fourths as great as that of the neck. A short distance be- 

 hind the head end, a distance six times as great as the diameter of the head, 

 there is a slight alteration in the structure of the oesophagus the significance 

 of which remains doubtful. The lining of the oesohpagus is not a very dis- 

 tinct feature. There is a very obscure, small cardia. The intestine, which 

 is separated from the oesophagus by a constriction, becomes at once about 

 two-thirds to three-fourths as wide as the body. At first its cells contain 

 but few scattered granules, but soon they are characterized by the presence 

 in them of loosely scattered yellowish-brown granules of variable size, the 

 largest of which have a diameter nearly one-eighth as great as that of the 

 body itself, and the smallest of which are very much smaller. These are 

 not arranged so as to give rise to any distinct tessellation. Toward the end 

 of the intestine the granules again become less abundant and smaller, so 

 that for some distance in front of the rectum there is only here and there 

 a granule. From the depressed and conspicuous anus the chitinized rec- 

 tum, which is a little longer than the anal body diameter, extends inward 

 and forward. There is no distinct pre-rectum. The tail end begins to taper 

 from a long distance in front of the anus, but tapers very gradually to 

 behind the anus. Thence onward it is inclined to be arcuate and tapers 

 regularly to near the terminus. Near the end it tapers more rapidly than 

 elsewhere, and finally comes to an almost acute point at the terminus. A 

 short distance in front of the terminus, however, the diameter is about half 

 as great as it is at the anus. There does not appear to be any spinneret, and 

 therefore, of course, caudal glands are absent. The lateral fields appear to 

 be about one-third as wide as the body. Nothing is known concerning the 

 excretory pore. From the slightly elevated vulva the vagina leads inward 

 nearly at right angles to the surface more than halfway across the body, 

 where it joins the single uterus, which extends backward. The ovary is 

 reflexed, and the blind end is about halfway back to the vulva. The eggs 

 occur in the uterus one or two at a time, and are very much elongated. They 

 are about six times as long as the body is wide, and about one-eighth as wide 

 as long, and are covered by a distinct, smooth shell. They are apparently 

 deposited before segmentation begins. The spermatozoa appear to be elon- 

 gated-ellipsoidal, and a little more pointed at one end than at the other. They 

 have a length one-fifth that of the body diameter. 

 68 



2 . 3 mm. 



3 -6 .7 .9 .7 

 The tail of the male is like that of the female in form and size, but 

 the anus is somewhat elevated. In front of the anus there appears to be a 

 ventral row of very obscure, broad, flattish supplementary organs. Perhaps 

 these ought to be described as locations of nerve endings rather than 

 as distinct organs. Their number remains doubtful, but there are about 



