PLATE 1 
EXPLANATION OF FIGURES 
1 Outline of a living specimen of the Scolex polymorphus. The stippled areas 
just behind the four bothria show the location of the faint red pigment spots 
seen in some specimens. Magnified about 45 diameters. 
2 Specimens of the Scolex polymorphus drawn from the living specimen to 
show the characteristic mode of attaching with all four suckers to the bottom 
of a dish in which they are being examined and the manner in which they fasten 
to one another. Magnified about 45 diameters. 
3 and 4 Outlines of the Scolex polymorphus drawn from living specimens 
to show other characteristic shapes. The area occupied by the large and small 
vascular trunks of either side and the terminal vesicle are added to fig. 3 as 
they appear in a stained specimen. The filiform appearance shown in fig. 4 
is often seen as the larvae draw themselves over a surface by the characteristic 
movements of their bothria. Magnified about 45 diameters. 
4a From a specimen stained and mounted whole, showing a portion of the 
body region on a large scale. The cuticle (cu), the larger and smaller excretory 
trunks (wt) and the conspicuous longitudinal muscle fibres (mf) are shown. The 
stippling indicates the distribution of nuclei in the parenchyma as it appears in 
optical section. Along part of the upper margin are shown the minute projec- 
tions which occur upon the cuticle in the posterior part of the scolex region and 
for a short distance along the body, finally giving place to the smooth cuticle 
as shown in the figure. Magnified about 200 diameters. 
5 Scolex of a young Phoreiobothrium triloculatum, taken from a sand shark 
artificially infected with Scolex polymorphus (see shark no. 3 of table 7). This 
view shows the division between two neighboring bothria along the mid-line of 
the figure. The characteristic pairs of hooks are shown attached along the 
line separating the upper and middle loculi of each bothrium. In this figure the 
subdivision of the posterior margin of the bothrium into three loculi, from which 
the specific name is derived, is not seen because the contraction of the lower mar- 
gin brings their surface at right angles to the general surface of the bothrium. The 
area on the mid-line of the figure toward the anterior end of the scolex, and marked 
by the closer stippling, appears in some specimens and may represent the ‘myzo- 
rhynchus’ of the Scolex polymorphus. Theminute spikes protruding from the neck 
region of the cuticle are shown in profile only. Magnified about 90 diameters. 
6 The same as the last figure. One of the bothria is shown in front view and 
the three posterior loculi are expanded so as to show clearly. Magnified about 
100 diameters. 
850 
