852 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [134] 



or rudimentary sense organs. A careful histological examination of 

 the scolex may throw some light on their true nature. 



Anatomy of mature segments. The male genital aperture is marginal 

 a little back of the middle. A lateral aperture was observed in a few 

 free segments. It was situated near the anterior end of the segment, 

 and is probably an opening for the discharge of ova, since careful search 

 failed to reveal any corresponding opening on immature segments. The 

 cirrus was not seen fully everted. The length in an alcoholic specimen 

 was estimated to be about 0.6 mm , and the diameter at base 0.12 ram . It 

 emerges from the center of a comparatively wide but shallow marginal 

 notch. The vagina appears to open immediately behind the cirrus in 

 the same marginal notch. The cirrus bulb is rather small, oval, and 

 directed slightly forward. The vas deferens lies in a coil in front and 

 at the base of the cirrus bulb, and enters the base of the bulb. The 

 ovaries are small obloug, or oval, and lie one on each side of the median 

 line and at about one-third the distance from the genital aperture to 

 the posterior end of the segment. Back of the ovaries are a number of 

 oval clear spaces. 



The ova are nearly globular. A living ovum measured 0.024 and 

 0.022 mm in its two diameters. Ova in the preserved specimens, mounted 

 in glycerine and slightly compressed, appear almost globular, and are 

 0.027 mm in diameter. They have smooth and rather thin shells, which 

 must be quite rigid, as no eggs were observed with the shell collapsed 

 or indented. In a few cases the ova are aggregated into a globular 

 mass about the middle of the segment and a little in front of the genital 

 aperture. This mass causes an abrupt swelling in the walls of the seg- 

 ment, which, upon slight pressure, bursts, releasing the eggs in vast 

 numbers. Ova were also seen lying along the median line and in 

 small clusters near the anterior end, whence they apparently find their 

 natural outlet. 



The anterior part of the mature segments which do not yet contain 

 ova is filled with oval or elliptical bodies, which, according to analogy 

 with other forms, doubtless represent the testes. In some these have 

 disappeared along the median line, leaving a median sinus which evi-. 

 deutly becomes a receptacle for ripe ova. There are usually only from 

 12 to 15 segments present in a single specimen. As the segments 

 mature they separate easily. 



On both occasions of finding this worm the chyle of the intestine was 

 swarming with them and with the free proglottides. A few were found 

 in the pyloric division of the stomach. The free proglottides, when 

 placed in sea- water, continued very active for several hours. They were 

 capable of active progressive motion by alternate contraction, and ex-, 

 pansiou of the body, during which each end often assumed the shape 

 and performed the function of a sucker. The masses of ova in the liv-^ 

 ing proglottides were, in some cases, ivory-white and opaque. In others 

 they passed from white through yellowish to brown. Others were yel- 

 lowish green. 



