48 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL,. 55. 



Female genitalia. — The ovaries (fig. 49) are elongated along the 

 longitudinal axis of the strobila, of the same size, and reniform to 

 fan-shaped, the interovarian field varying correspondingly from oval 

 to almost quadrilateral. The vitellarium is roughly triangular in 

 outline, the anterior angle projecting a short distance into the inter- 

 ovarian field and occasionally suppressed at this point to form a 

 truncated or even invaginated structure for the reception of the 



shell-gland. The vitellarium is 



V^ 



/ 









-R ®" '^^ ^ ^ 





,<^?.«^. 







often irregular or asymmetrical 

 and in some segments may even 

 be elongated along the longitudi- 

 nal axig of the strobila, a quite 

 distinctive feature (fig. 50). The 

 vitellarium does not extend lat- 

 erally as far as the ovaries do. 

 The shell-gland is comparatively 

 large, at times distinctly in tlie 

 clear near the anterior apex of 

 the vitellarium and at times ap- 

 parently in contact with the vi- 

 tellarium or occupying an in- 

 vagination at the anterior apex 

 of the vitellarium. The vagina 

 follows the general contour of 

 the portion of the cirrus pouch 

 lying nearest the lateral margin 

 of the segment, being straight 

 when the cirrus pouch is straight 

 and following the concavity 

 when the pouch is concave pos- 

 teriorly. It then bends abruptly, 

 usually at right angles, but at 

 times at an obtuse angle or again 

 at an acute angle back toward 

 the margin of the segment. It 

 Ihen turns medially and after 

 pursuing a short wavy course, 

 with usually two crests, or even 

 niaking another loop, it swings in a wide curve around the nearest 

 ovary to the receptaculum seminis in the interovarian field. In gravid 

 segments the median stem of the uterus is very wide and has from 12 

 to 15 wide lateral branches which in turn send out wide secondary 

 branches. The median field of the narrow segments is thus reduced 

 to nearly a solid mass of egg3, the space between the wide uterine 

 areas being very small. The eggs are nearly spherical and are 25 to 

 30 |x in diameter. 



1 1.,. 50.- 



mm. 



-MULTICEPS GAIGERI. MATURE SEGMENT 

 SHOWING THE OCCASIONAL ELONGATION OF THE 

 VITELLARIUM ALONG THE LONGITUDINAL AXIS OF 

 THE STROBILA. FROM HALL, 191()rt. 



