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, 



