F. J. Meggitt 
271 
segments ripen sooner : this would account for the discrepancies in the 
statements of Cohn and Magelhaes. 
The testes are spherical bodies, 12 in number and 0-045 mm. in 
diameter, lying in a single row on the dorsal surface of the posterior end 
of the proglottis (PL XX, fig. 4). From the end testis on each side, 
a narrow vas deferens runs along the posterior margin to the centre, 
receiving on the way a number of short and minute vasa efferentia from 
the testes, one vas efferens from each testis. Arriving at the centre of 
the proglottis, the two vasa deferentia unite to form a single duct 
running anteriorly to the anterior border of the proglottis. There it 
bends at right angles to its previous course and forms a series of elongated 
coils, after which it enters the cirrus sac. As Cohn states, there is no 
vesicular seminalis, the coils of the vas deferens being greatly dilated and 
filled with spermatozoa, thus functioning as one. The walls of the coiled 
portion of the vas deferens consist of a slight muscular layer and an 
outer membrane, external to which is an irregular layer of nuclei. On 
the smaller ducts no observations could be made owing to their small size. 
The cirrus varies greatly in position in the different segments : it 
often extends horizontally into the proglottis but may be so directed 
that its hinder end touches the posterior border of the proglottis and 
its front end the anterior border : there are all stages between these 
two extremes. All cases though agree in having a sudden twist, either 
posteriorly or anteriorly, in the anterior quarter of the sac. 
The vas deferens (0-0046 mm. diam.) enters the cirrus sac at the 
posterior end and runs with one or two curves as far as the bend just 
mentioned. Here it doubles back upon itself, extending nearly to the 
posterior end, when it again bends round to open into the cirrus. This 
latter is almost straight and runs through the anterior half of the cirrus 
sac and the bend to open into the sinus close to the opening of the 
vmgina. 
The cirrus sac consists of a definite dark staining membrane en¬ 
closing a space almost entirely filled by the vas deferens and cirrus, 
the interstices between them being occupied by a fibrous tissue. 
Xumbers of large nuclei are scattered through the sac. The vas 
defei>ens itself, owfing to the increased width of the muscidar layer, is 
shghtly wider inside the sac than outside, and has a peculiar circular 
striation at right angles to its length : otherwise it has the same structure 
as before. I should assume this striation to be due to the presence 
of circular muscles, although the rings are relatively so far apart that 
they appear entirely isolated from one another. The cirrus itself is a 
