ANATOMY OF TANIA MEDIOCANELLATA, v 
vascular canal (fig. 2, e; fig. 3, d), immediately below which 
it is constricted and divided from that of the next segment 
by a fibrous diaphragm (fig. 3, e), and where the lateral edge 
meets the sheath of the penis there the radiating strand con- 
necting it with the side of the segment is much thicker than 
elsewhere, and many of the more central fibres are lost upon 
the external surface of the sheath, in fact greatly assisting it 
in its formation. From the inside of the boundary fibrous 
processes pass across from side to side of the visceral space, 
giving a slinging support to the components of the genera- 
tive systems, uterus, ovarian glands and tubes, vas deferens 
and testicular bodies, encircling these as in a capsule and 
separating them from the soft intervening substance. ‘This 
substance, which fills up the space which would otherwise be 
left between the curved outlines of the visceral subdivisions 
and the internal surface of the boundary, is of a granular 
albuminoid character, thickly studded with small fat-granules 
and globules only (fig. 2, 6; fig. 13,6). Laminated calcareous 
nodules are sparsely seated in the fibrous boundary and 
its main prolongations inwards, but their number is very 
small, and hence in this respect there is a marked contrast 
to the thickly set body structure environing it. 
Male Generative System.—The genital orifice at the side 
of the segment is ovoid in shape, much more in transverse 
diameter than vertically ; its edge is thick and tumid, and 
from the orifice a pit extends inwards to the depth of +; in., 
expanding vertically until the height and transverse measure- 
ments are equal. At the centre of its inner wall, on a slight 
oval prominence, are the external orifices of the penis and 
vagina, the former above the level of the latter, but in close 
contiguity to it (fig. 2,9,h; fig.10). This pit is produced 
by an inflexion of the skin and subjacent muscular layers, 
and not uncommonly there is a slight depression of the ex- 
ternal surface of the flat sides of the segment corresponding 
to the floor of the pit internally and caused by the tumid lips 
of the aperture. ‘The skin from the genital pit is observed 
to form a sort of prepuce and to pass in by the side of the 
penis for a short distance, constituting a groove, and then to 
lose itself on the external surface of the organ (fig. 7, c); the 
circular muscular fibres of the body substance also curve in, 
and, thickened by transverse fibres and fibrous tissue, compose 
a sheath to the penis externally. The penis (fig. 1, e; fig. 
2,9; fig. 7) in its retracted condition is a musculo-membra- 
nous elongated double cylinder, ~; in. long by 1,5 in. 
diameter, tapering towards the tip, but expanding at its other 
extremity into a globular bulb, 4, in. thick (fig. 7, e, f). 
