208 : -DR. F. WOOD-JONES ON THE 
into a common chamber having a wide lumen, separate again as 
they approach the pelvis, and the lumen of each individual duct 
becomes occluded by the proliferating epithelium of its walls 
(Pl. II. fig. 2). In this occluded state they pass as epithelial 
cords dorsad to the urinary canal and, sweeping into the pelvis 
caudad to it, may be traced past the openings of the minute 
Wolffian ducts. 
From this point onward each Mullerian cord may be traced as 
a delicate epithelial strand caudad and ventrad of the urethra, 
still in intimate relation with the wall of the urethra, but 
apparently altogether separated trom its lumen. 
This is the state of affairs at the caudad bend of the urethra, 
From here the urethra and the crura clitoridis turn cephalad 
again to the genital tubercle, the tissues of which they penetrate ; 
but the Mullerian strands do not take part in this cephalad bend, 
for they continue their course towards the base of the genital 
tubercle rather than towards the central mass of its tissues. It 
is here that the most curious feature in the development of the 
female genital system of Talpais seen. The genital tubercle itself 
is, of course, covered by the general many-layered cutaneous epl- 
thelium which here shows but few hair rudiments. At the lateral 
and inferior margins of the genital tubercle just where it joins 
the general skin of the perineal region, the deeper layer of the 
perineal skin dips inwards into the perineal tissues as two lateral 
cords which become continuous below the sides of the urethra 
with the similarly solid Mullerian cord. 
I have spoken of these solid cords as being bilateral, but in the 
embryo of 33 mm., of which I have serial pelvic sections, I have 
been able to trace the continuity of the surface epithelium with 
the Mullerian cord only upon the left side, although in the same 
situation upon the right side is a well-marked stream-line of 
the cells of the perineal tissues (Pl. III. fig. 1, the figure is 
reversed), This unilateral condition of the epithelial ingrowth 
is worthy of notice, for again at a later stage I have observed the 
same thing : and it becomes significant when taken in conjunction 
with the observation of Adams that the adult vagina is perforated 
by bilateral breaking down of the perineal tissues. The changes 
that have taken place in the interval between the 27 mm. stage 
and the 33 mm. stage are not really very great, for the rudiments 
of all the conditions described in the 33 mm. embryo are already 
present in that of the 27 mm. embryo, Although in the younger 
example the Mullerian ducts definitely join the urethral wall at 
their lower ends, still, even at this stage, an epithelial prolongation 
from them may be followed around the caudal bend of the urethra 
towards the base of the genital tubercle, and, moreover, an epi- 
thelial ingrowth from the skin of the base of the genital tubercle 
is already in process of development. In this younger embryo 
the ingrowth is again unilateral, being found in my series only 
upon the right side (Pl. IT. fig. 1: the figure is reversed). 
The embryonic condition of the female passages is therefore a 
