142 BULLETIN OF THE 
tioned above, they are shorter than any of the males, though in diam- 
eter intermediate between the extremes of the latter. The only female 
among the specimens sent by Professor Verrill measured 60 mm., which 
still is shorter than the average male, and far below some of the large 
males in that collection, one of which reached even 200 mm. in length. 
Not only is the female smaller than the male, but also far less plenti- 
ful. Among the sixty-five specimens which I have examined, there were 
but four females, a proportion so small as to suggest that it is due in 
part to other causes than the greater number of males produced. Possi- 
bly the female, being the less active of the two, is not so often at the 
surface, and consequently is less frequently caught. 
From the general external appearance one easily recognizes three 
main parts of the body, a short semi-transparent anterior portion, a very 
long opaque middle region, and a terminal part, which resembles in 
transparency and length the anterior portion. The anterior region goes 
over into the body proper without any external demarcation. There is 
no, constriction at this point in the living animal, and although one is 
usually found here in alcoholic specimens, it is surely the result of con- 
traction or collapse. If, however, the living animal be studied under a 
compressor (Fig. 2), or still more clearly if the anterior part of the body 
of an alcoholic specimen be examined in clove oil, this clear portion is 
seen to be cut off from the general body cavity by a transverse parti- 
tion (Plate I. Fig. 8), thus forming an anterior chamber, which will be 
considered in detail later, 
Following this the body proper is uniformly opaque in appearance, and 
constitutes the greater part of the entire length, passing over insensibly 
near the posterior end of the body into the posterior translucent region, 
which is however by no means so clear as the anterior part. The body 
terminates in the female abruptly, but in the male it is prolonged into a 
ventrally curved conical organ with a terminal opening. The general 
appearance of the worm is shown in Figure 1, which represents in its 
natural size one of the largest specimens captured. The difference be- 
tween the posterior end of the male and that of the female is easily seen 
by comparing views of the two as seen under a dissecting miscroscope 
(Plate I. Figs. 4,5). The female is represented in the act of discharging 
eggs. The end of the body of the male differs greatly in appearance in 
different individuals. It may be nearly straight with only the intro- 
mittent organ turned slightly ventrad (Fig. 89), or for a greater or less 
distance anterior to this point it may be flexed ventrally or even coiled 
(Fig. 1). The end of the female is on the other hand nearly straight, 
