426 SIR WILLIAM TURNER 
generally cylindriform, though it showed in each transverse section from four to ten or — 
twelve bulgings on the outer surface of its wall. In many sections each bulging 
seemed to contain a nucleated cell, but under higher powers this was not so evident. 
In some sections a sharp line, apparently the lining membrane of the duct, was con- 
tinued round the wall, as if to shut off the bulgings with their contents from the lumen. 
In others, again, the bulgings projected into the lumen, and were not shut off by a — 
lining membrane. When the wall of the oviduct had fused with that of the cement 
duct, a layer of nucleated cells was traced from the outer surface of one duct to 
that of the other. In some transverse sections through the oviducts the lumen 
contained a delicate network of fibres which radiated from the centre to the periphery. 
The wall of the cement duct was several times thicker than that of the oviduct, 
except at the spot where it was joined either by the intermediate band or by the 
wall of the oviduct. The lumen of the cement duct, especially near its lower end, 
frequently contained a plug of cement which almost filled the tube (figs. 20-23). 
Receptacula,—Lach receptaculum seminis was situated at the side of the ventral 
space near its anterior part. Its antero-posterior diameter was longer than the trans- 
verse, and the wall lying next the ventral space was sometimes thinner, at others 
thicker, than the opposite wall; the anterior part both of wall and lumen had frequently 
a tortuous appearance, as if slightly convoluted, and from its lower end a short canal 
arose, which ended in the genital orifice. The lumen almost invariably contained a 
plug of cement, antero-posteriorly elongated like the receptaculum itself (figs. 29, 30). 
Associated with the lower part of the genito-abdominal segment was a distinct 
muscular arrangement, the fibres of which were transversely striped, but in: addition - 
some bands belonging to the lateral mesenteries consisted of unstriped fibre. The 
striped muscles arose from the chitinous wall, some bundles ventral to the mesentery, 
others within its substance; they passed downwards and inwards, and in the trans-_ 
verse sections the fibres were usually cut through transversely or obliquely. Some 
fibres were attached to the wall of the oviducts; but the greater number reache 
the posterior end and outer wall of the receptacula, to which they were attached 
by tendon-like structures (fig. 28). Owing to this arrangement, the wall could be 
drawn outwards and the lumen of the receptaculum made larger, a condition which — 
doubtless prevailed when the ova, the cement, and probably the spermatic fluid also, 
passed into it. 
Ova strings.—These were about the thickness of fine sewing-thread. They began 
at the genital orifices and floated in the sea in which the animal lived. The outer part 
of each string was formed of cement, and the space which it inclosed would have contained 
the ova had they been ripe for extrusion. When examined microscopically, transverse 
lines closely set together were seen to pass from one to the other side of the inclosing 
cement. In my specimens I saw no ova in the ova strings. The ovarian ova were 
unripe, and there was an absence of ova in the oviducts and receptacula. When 
sections were made through the ova strings, the space inclosed by the cement was seen 
