MONCECIA — MONOTREMATA. 
3oG 
the sexual products of botli sexes are expelled by ducts opening from 
the pallial region, a position still retained by the female aperture in 
this group. There is also a gi’eater complexity and differentiation 
of the albuminous glandular part of the female system, probably in 
correlation with the albuminous mass within which the eggs of the 
Limnccldiv are deposited. 
The Monotremata (judros, single ; ’rp"]p-n, cavity) embrace those 
bermapbrodite species in wbicb both male and female organs open 
exteriorly by a common o,perture ; they exhibit the highest organiza- 
tion attained by the sexual organs in the species within the sphere 
of our studies aciiuiring a greater complexity and wealth of acces- 
sory organs. The external aperture, though common to both series 
of organs, yet during extrusion exhibits a terminal female opening 
and a masculine lateral one. 
For convenience of study the Monotremata may be separated into 
three groups ; Haplogama, Gynogama, and Belogama. 
The Haplogama (d7rA.oi's', simple; ydpo^;, marriage) are the most 
simply organized of the j\Ionotremata, establishing them as regards 
their genitalia to be the most ancient 
type ; their organization comprising on 
the male side the ovotestis, the her- 
maphrodite duct which ends in a 
coecum at the base of the ample albu- 
men gland, the prostatic tract which is 
adherent to the glandular oviduct, 
but later becomes free as the vas 
deferens, and joining the penis which 
is enclosed by a sheath, to which a 
retractor muscle is affixed. The 
female organs embrace the ovotestis, 
the oviduct, and the vagina, where 
the .spermatlieca usually opens. 
Except for the presence of an 
appendix as an adjunct to the penis 
in certain species, and which may 
possibly be a relic of a primitive flagellum, such as is still per- 
sistent in liit/iyiiid and other groups, and of a so-called appendicula 
on the female side, there are no accessory organs such as those 
developed in the Stylogama. 
F IG. 650. — Reproductive organs of Zua 
Itibrica (Miill.), X 12 (after Ihering), illus- 
trating the Cryptophalliate Haplogama. 
s.d. sperm duct; ZKd, vas deferens; 
p.s. penis sheath; r. retractor muscle; 
ap. appendix ; a.^. albumen gland ; 
OIK glandular oviduct ; sp. spermatheca ; 
V. vestibule ; v.gL vaginal gland. 
