ON PENNELLA BALAANOPTER. 425, 
Cement Glands.—The pair of cement glands were situated in the upper part of 
the genito-abdominal segment. In a considerable part of their extent they were 
alongside the ovaries, and corresponded in their general relations; but in some of 
the transverse sections ovarian tubes were present without adjoining cement glands, 
and in others portions of the cement glands were seen with no ovarian tubes in 
proximity tothem. The ovaries and the cement glands were therefore not quite equal in 
extent. When both were present in the same transverse section the ovaries lay across 
the mesial plane, between the two cement glands, the latter of which were placed in 
close relation to the dorsal surface of the lateral mesenteries. When the cement glands 
alone were present they lay close to the mesial plane of the parasite, and were separated 
from each other by a prolongation of the dorsal space (figs. 22, 23). 
Hach cement gland consisted of a coiled tube inclosed in a membranous capsule, 
from the inner surface of which fibrous processes passed between the coils of the tubes. 
Lying close to the outer surface of that part of each capsule which was next the inter- 
posed dorsal space, well-marked nucleated cells, which possessed one or more processes, 
were seen; and as similar cells were present in the membranous wall of the space where 
it was next the pigmented lining membrane of the chitinous envelope, these cells should 
be regarded as belonging to the wall of the space rather than to the capsule of the 
cement gland. The coiled tube of the cement gland, in making the section, had been 
cut into short picces, transversely, obliquely and longitudinally. It had a well-defined 
wall, which was lined by a layer of short cubical cells. The lumen of the tube con- 
tained a dimly granular substance which stained with carmine and with hematoxylin. 
No sign of an ovum could be seen in the tube. 
Oviducts, Cement ducts, Receptacula, Ova strings.—HKach ovary and cement gland 
had a characteristic duct. In the numerous transverse sections made through the 
genito-abdominal segment, except at the highest part of the ovary, an oviduct and a. 
cement duct were seen on each side of the mesial plane. They were placed ventrally 
to the lateral mesenteries, and in relation to the sides of the ventral mesial space. 
They had evidently emerged near the upper ends of their respective organs, and had 
passed forward into the ventral region of the segment, down which they ran to the 
receptacula. The cement duct on each side was in front of the oviduct, and was 
separated from it in the upper part of their course by a slight interval. A slender 
intermediate band passed from the wall of one to that of the other, and at its junction 
with the cement duct the wall of that duct was much thinner than im other parts of its 
circumference. Lower down in the segment the walls of the two ducts came in contact 
with each other and fused together. Before their lumina became continuous with each 
other, the oviduct diminished in its calibre, and the cement duct became elongated 
antero-posteriorly. The intermediate part of the common wall then disappeared, and 
the receptaculum was formed a little above the genital openings (figs. 20-23, 25, 26). 
The ducts were readily distinguished from each other, both by their relative 
position and their characters. The wall of the oviduct was much the thinner, and was. 
TRANS. ROY. SOC. EDIN., VOL. XLI. PART II. (NO. 18). 63 
