570 
Cestodes from Selachians 
measuring about 8 x 0-30—0-36 mm. anteriorly where narrowest 
and 0-7—0-8 mm. posteriorly. The segments broaden and lengthen 
posteriorly for some distance, then slightly decrease in breadth, the 
last segments being much longer than broad. 
Genital openings irregularly alternate, situated a little anterior 
to the middle of lateral margin or at a distance of one-third of 
a segment-length from anterior border. Testes distributed throughout 
the space among the other genital organs ; oval in shape, measuring 0-06— 
0-07 X 0-04—0-05mm. Vas deferens with thin wall; much coiled near 
the anterior side of cirrus pouch; measuring 0-01—0-023 in diameter, 
much coiled in the cirrus pouch, its muscular wall thickened and lined 
by a layer of cuticular spinules and surrounded by well nucleated 
cell masses. Cirrus opens into the common genital cloaca. Cirrus 
pouch with thin wall, large, oval in shape extending to near aporose 
side of medullary field. 
Ovary situated near the posterior end of segment, consisting of 
four irregular lobes, each lying on dorsal and ventral sides of segment. 
Inner ends of ovary converge toward the median line of segment wherje 
they unite to form an isthmus of ovarian groups. Yolk glands consist 
of four longitudinal columns running antero-posteriorly dorsally and 
ventrally to the lateral nerve cords on both sides; they lie between the 
marginal and medullary fields; each column elongate oval in cross 
section. Shell gland spherical or oval and situated a little postero- 
dorsal to the isthmus. Uterus running longitudinally along ventro- 
median line of each segment; connected with shell gland by a small 
duct running from shell gland anteriorly on dorso-median line and 
opening into uterus about midway along segment. Vagina begins 
with common genital cloaca at dorsal side of cirrus opening, runs 
inward along the anterior side of cirrus pouch, bends posteriorly near 
the inner end of pouch and passes back to the ovarian region where it 
rapidly narrows, and, pursuing a winding course, unites with the oviduct. 
United canal runs dorsally to open into shell gland. Wall of vagina and 
oviduct of similar structure being composed of thick muscular layers 
and lined with the cuticular spinules 
Host. Cynias manazo (Bleeker), spiral valve. 
