492 PENTASTOMIDA CHAP. 
Pentastomids are bisexual. The males are as a rule much 
less numerous and considerably smaller than the females, although 
the number of annuli may be greater. 
The ovary consists of a single tube closed behind. This is 
supported by a median mesentery. Anteriorly the ovary passes 
into a right and left oviduct, which, traversing the large hook- 
gland, encircle the alimentary canal and the two posterior nerves 
(Fig. 258). They then unite, and at their point of union they 
receive the ducts of the two spermathecae, usually found packed 
with spermatozoa. Having received the orifices of the sperma- 
theca, the united oviducts are continued backward as the uterus, 
a highly-coiled tube in which the fertilised eggs are stored. 
These are very numerous; Leuckart estimated that a single female 
Fia. 258,—Diagrammatic representation of the alimentary, secretory, nervous, and repro- 
ductive systems of a female Porocephalus teretiusculus, seen from the side. ‘The 
nerves are represented by solid black lines. (From W. Baldwin Spencer.) 
1, Head-gland ; 2, oviduct ; 8, hook-gland; 4, mid-gut; 5, ovary; 6, hind-gut; 7, 
vagina ; 8, uterus; 9, accessory gland ; 10, spermatheca. 
may contain half a million eggs. The uterus opens to the 
exterior in the mid-ventral line a short distance—in P. teretius- 
culus on the last ring but seven—in front of the terminal anus. 
In L. taenioides the eggs begin to be laid in the mucus of the 
nose some six months after the parasite has taken up its 
position. 
The testis is a single tube occupying in the male a position 
similar to that of the ovary in the female. Anteriorly it opens 
into two vesiculae seminales, which, like the oviducts, pierce the 
hook-glands and encircle the alimentary canal (Fig. 257). Each 
vesicula passes into a vas deferens with a cuticular lining. 
Each vas deferens also receives the orifice of a muscular caecal 
ejaculatory duct, which, crowded with mature_ spermatozoa, 
stretches back through the body. Anteriorly the vas deferens 
passes into a cirrus-bulb, which is joined by a cirrus-sac on one 
side and a dilator-rod sae on the other, structures containing 
