26 PROCEEDINGS OF THE NATIONAL MUSEUM VOL. 92 
Specific description.—Pseudoscolex very highly developed, and 
complexly crinkled as in old specimens of TJ. thysanocephalum, but 
larger than in that species, measuring 2.8 to 4.2 mm. across. 
Neck 2 to 3.3 mm. broad at junction with pseudoscolex, narrowing 
rapidly to a diameter of 1.4 to 1.7 mm. less than a centimeter from 
the head. This diameter is uniformly maintained for a long distance 
but gradually increases again to a diameter of about 3 mm., which 
is maintained throughout most of the length of the worm. Total 
length of longest strobila 48 cm. Cuticle of entire strobila marked 
by chitinous reticulations about 5yu to 7y thick, enclosing irregular 
spaces 50u to 120u across and giving a peculiar and very characteristic 
scaly appearance. Apparently three pairs of longitudinal excretory 
ducts are present: A very broad ventral one accompanied by a narrow 
dorsal one, dividing the segment transversely about 1:2:1, and an 
additional pair of fairly broad outer ducts much nearer the margins. 
Segmentation begins between 15 and 20 cm. from head. At 25 cm. 
the segments are 0.2 to 0.25 mm. long; at 40 cm., 0.7 mm. long; and 
at 45 cm., 1.5 mm. long. No ripe segments present. 
Genital pores irregularly alternate, majority opening at left, 
situated a little behind middle of lateral margin. Cirrus sac very 
long (1.3 mm.) and in oldest segments 450 broad, curving forward. 
Vas deferens much coiled, especially after leaving cirrus pouch, 
where the coils occupy the area bounded by the cirrus pouch, anterior 
loop of vagina, and uterus. Testes very numerous, about 60u to 80u 
in diameter, occupying practically all available space between the 
outer excretory ducts. Vagina les just anterior to cirrus pouch, with 
its mouth just in front of the opening of the pouch. Its distal por- 
tion is enlarged with thickened walls, narrowing to a thin-walled tube 
just inside the inner excretory ducts; it makes a broad curve forward 
and then continues sinuously along the midline toward the posterior 
end of the segment. Here it has several loops, surrounded by Mehlis’s 
gland. The ovaries extend across the posterior part of the segment 
between the outer excretory ducts, each one about 900yu broad and 
300u anteroposteriorly. The uterus runs forward dorsal to the 
vagina on the median line; it develops into a series of kinks, which 
Ficure 2.—New Cestropes From FL oripa SHARKS. 
a-d. Thysanocephalum rugosum, new species: a, Pseudoscolex; 6, portion of pseudoscolex 
much enlarged, showing thickened crinkled edges; c, mature segment about 45 cm. 
from head, cuticle and layer of yolk glands stripped off; d, younger segment about 
30 cm. from head. 
e-1. Diplodtobothrium springeri, new genus and species: e, Scolex; f, mature segment about 
28 cm. from head, cuticle and layer of yolk glands stripped off; g, ripe segment 
about 40 cm. from head, cuticle and layer of yolk glands stripped off; h, portion 
of proboscis indicated by “A” on fig. 2, from opposite side; 1, partially everted pro- 
boscis, shaded part indicating invaginated portion. 
