F. J. Meggitt 
585 
Male Organs. 
The male organs of the first group present a peculiarity so far not 
recorded. They are usually arranged in pairs, each pair having a 
common opening into the central space. The vesicula seminalis and 
vas deferens of the more anterior of the pair run posteriorly and those of 
the more posterior riui anteriorly, the cirri of both opening into a common 
duct which then opens into the central space. This arrangement is 
occasionally varied by segments in which the male ducts do not join 
either those of the preceding nor those of the succeeding segment: 
in that case the ducts are always incomplete, a vesicula seminalis being 
present, but no cirrus and no opening. 
The common duct (Fig. 6, c.d.) of each pair of male genital organs 
is a short tube, enlarged at its outer end into a small sinus ( g.s .). From 
this it runs towards arm 2, and after a short course reaches the point 
where the two cirri open into it, there ending blindly. The arrange¬ 
ment of the other ducts in each of the pair is the same, if allowance be 
made for the difference caused by one being situated anteriorly and one 
posteriorly. The more anterior cirrus (Fig. 3) runs slightly anteriorly 
and towards the junction of arms 1 and 2 until it reaches the lateral 
limit of the central space. Here it bends round and opens into a large 
vesicula seminalis (a.v.s.). This runs posteriorly and retraces the 
course of the cirrus nearly to the lateral limit between arms 1 and 3 
of the central space where it contracts to an exceedingly narrow tube 
passing through a thick highly muscular cylindrical mass (c.s.) 0-15 mm. 
in transverse diameter. The other cirrus meanwhile has run in a similar 
manner first posteriorly and then anteriorly, opening into a vesicula 
seminalis (p.v.s.) which also opens into this muscular mass. 
At the posterior and anterior limits respectively in this organ the 
two ducts often fuse. This is the last point where they come into 
contact with each other. From here, one runs anteriorly and one 
posteriorly for some distance through this muscular organ, finally to 
open into a second vesicula seminalis (i a.'v.'sp.'v.'s.'). From a 
comparison of transverse sections of the tri-radiate Cestode with similar 
sections of a normal one, I am inclined to think that the muscular organ 
(c.s.) just referred to is the extreme inner end of the cirrus sac. It is 
however much thicker and much more muscular than in normal speci¬ 
mens and usually is not continued round the cirrus and first vesicula 
seminalis. Sometimes the two latter are surrounded by a membrane 
but usually they are free. On the other hand, in normal specimens there 
