148 
Transactions of the Society. 
To commence with the receptaculiim seminis. I did not describe 
or find such an organ in TJropoda Krameri, nor am 1 aware that it 
has been described in any Uropoda, or indeed in any of the Gamasidde ; 
nevertheless in Uropoda ovalis it is a large and unmistakable organ, 
which, in most of the numerous specimens that I dissected, was full of 
spermatozoa; and it will be. seen further on that receptacula seminis 
exist also in U. vegetans, although they differ widely from the azygous 
organ of the present species. 
The position of the receptaculum seminis in U. ovalis is shown in 
figs. 1, 2, rs, and the organ itself on a larger scale is drawn at fig. 8. 
It is placed longitudinally and horizontally in the median line, and 
runs below the vagina ; it is long and sac-like, widest at its posterior 
extremity, with a concave hind margin and rounded posterior corners ; 
it narrows gradually until near the mouth, when it widens again more 
rapidly, and its anterior edge is attached to a chitinous strengthening 
bar (fig. 8, ar). This bar is not straight ; its shape may be best 
gathered from the figure ; its central portion forms a pointed arch, 
which stands in a sloping direction upward and backward. The bar 
is sunk in the wall of the lower part of the posterior end of the 
vestibule, and the arch therefore forms an entrance from the vestibule 
to the receptaculum seminis, which is fairly accessible from the ex- 
terior after the genital plate has been got out of the way. 
Above the opening of the receptaculum seminis, still in the median 
line, but near the top of the wall of the vestibule, is the opening of 
the neck of the vagina (fig. 2, &c., nf. The vagina itself is a more 
or less globular organ, sometimes slightly constricted in the middle ; 
it has thickish muscular walls, and is capable of considerable disten- 
sion. It is quite of the type of the same organ in U. Krameri and 
in the Orihatidse. The neck, however, exhibits some difference, viz. 
at the anterior end the vagina is suddenly contracted by powerful 
ring-muscles, so as to form a narrow neck n, which is also provided 
with longitudinal muscles. This neck finally expands again, still 
retaining its muscular and folded condition, and curves forward, its 
upper edge overhanging the lower (fig. 5, n ^) ; this upper edge 
overlies, and is attached to, the posterior end of the perigynum (fig. 3). 
The lower and lateral edges of the expanded neck of the vagina are 
not attached to anything, except that to each lower angle, near the 
edge of the opening, a tendon (fig. 6, P) is attached. This tendon 
is the termination of a muscle {m^) which itself arises from the ventral 
plate, and, when in action, would draw the lower edge of the neck 
downward and backward. 
The perigynum (fig. 7, and figs. I, 3, 4, 5, &c., ^g) is a very 
singular structure; it is best described as being somewhat of the 
shape of a shoe, concave on its dorsal and convex on its ventral surface. 
The heel of the shoe turns sharply upward (figs. 6, 7), and ends in 
a narrow portion (figs. 3, 4, 7). The upper edge, or framework, of 
the heel of the perigynum is composed of a strong chitinous bar. 
