54 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 70 



of ripe proglottides, in which the uterus occupies the greater part of 

 the interior, 0.23, breadth, anterior 0.35, posterior 0.60. In strobiles 

 which had been placed in fresh water before fixation, the proglottides 

 presented a great variety of shapes, exhibiting a tendency to lengthen 

 and become more or less campanulate. Thus, at one point a proglot- 

 tis has the following dimensions : Length 0.29 mm., breadth, anterior 

 0.14, posterior 0.32; the third segment back of this, length 0.15, 

 breadth, anterior 0.35, posterior 0.42; the sixth segment back of the 

 latter, length 0.32, breadth, anterior 0.17, posterior 0.34; ripe seg- 

 ments, length 0.39, breadth, anterior 0.28, posterior 0.53. 



The genital pores are unilateral and situated in front of the mid- 

 dle of the margin. The cirrus is long, slender, and smooth. The 

 cirrus-pouch has thick muscular w^alls, and has a tendency to press 

 against the marginal wall so as to make a protruding bulge in the 

 outline of the lateral margin. The cirrus-pouch extends antero- 

 mediad, and coils of the vas deferens lie at the median line near the 

 anterior border. The exact number of testes was not made out, but 

 they appear to be at least 12 in number. They lie dorsal to the 

 ovary and extend somewhat beyond its posterior and lateral borders. 

 The ovary, while presenting a variety of appearances in proglottides 

 of different stages of development, becomes more or less lobed (fig. 

 177). It lies ventral to the testes, and the relatively small and com- 

 pact vitelline gland lies immediately posterior to it. The uterus 

 differs markedly in appearance even in adjacent proglottides. As 

 it matures it becomes profoundly lobed (fig. 180). Ultimately the 

 lobes become indistinct and the uterus comes to occupy practically 

 all the interior of the proglottis. So far as can be made out the 

 eggs are oval, with thin, membranous shells, the diameter of which 

 is at least as much as 0.036 mm. ; diameter of onchosphere 0.018. 



The longtitudinal muscles are not sharply set off into two layers, 

 but the fascicles on the medullary side are fewer and larger than 

 those on the cuticular side, as in V. parvispine (fig. 187). 



The genital ducts pass between the longitudinal excretory vessels. 

 The latter are indistinct in most of the sections. The dorsal vessel 

 is minute, the ventral vessel much larger. In one series of sections 

 the lumen of a ventral vessel, crowded by the gravid uterus and 

 with collapsed walls, measured 0.018 by 0.003 mm. in the two 

 principal diameters; the lumen of the dorsal vessel was about 0.002 

 mm. in diameter. 



RECORD OF COLLECTIONS 



Nycticorax nycticorax naevius: 



1905, October 19. — Few, small, no scoleces. 



1906, September 26. — Fragments of strobiles; no scoleces. 

 1906, September 28. — Several fi'agments, with at least one 



scolex. 



