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ea PROCEEDINGS OF THE NATIONAL MUSEUM. 109 
with minute bristle-like spines, and when fully everted with a short 
conical tip devoid of spines. 
In one specimen measuring 8 millimeters in length the posterior seg- 
ments contained ova, with embryos, measuring about 0.025 millimeter 
in diameter. 
The proboscis when fully extended is at least as long as the head, ex- 
_ pands at the apex, where it bears a circle of ten hooks. These are 
_ bent somewhat abruptly near the end, but on the whole are rather 
- strai ght. 
One specimen was observed which agreed with the others in the 
number and shape of the hooks, but the hooks measured only 0.04 
millimeter instead of from 0.05 to 0.055 in the others. The proboscis in 
¥ 
this specimen was elongated, cylindrical and 0.4 millimeter in length, 
or over two and a half times the length of the head. An average 
specimen 7 millimeters in length had the following dimensions, in mil- 
limeters: Diameter of head, 0.18; length of bothrium, 0.15; length of 
proboscis, 0.16; diameter of proboscis at apex, not including hooks, 0 08; 
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diameter of Givin of hooks, 0.12; diameter of proboscis at base, 0.04; 
diameter of neck, 0.03; length of first distinct segments, 0.025 ; breadth 
of first segments, 0.14; length of lastsegments, 0.37 ; breadth of last seg- 
“ments, 0.7. In another specimen the diameter of the head was 0.24 
millimeter and the diameter of the proboscis at base 0.025 millimeter, 
_ while the other dimensions were nearly as in the detailed measurements 
given. 
The specimens of the second group do not present any constant dif- 
ferences, other than size, of sufficient importance to justify their refer- 
ence to a distinct species or even variety. The head appears to be 
broader, in some cases at least, in proportion to the length, and the 
middle segments are much more closely crowded together; the cirrus 
is also possibly a little more slender. Embryos were observed, 0.04 by 
0.03 millimeter in the two principal diameters, with spines measuring 
0.01 millimeter in length. 
Detailed measurements of a specimen 27 millimeters in length yielded 
the same results for hooks, proboscis, and segments as were obtained 
from small specimens of the first group. 
Those referred to the third group were characterized by having thick 
strobiles in which the segments were relatively short and crowded to- 
gether. In one specimen 15 millimeters in length the last segments 
were much crowded, measuring 1.1 millimeters in breadth, and 0.13 
millimeter in length, otherwise as in the first two groups. The cirrus 
| pouches in some of these larger specimens are inclined at an angle of 
nearly 45 degrees with the margin; the elliptical body beside the cirrus 
pouch is not distinct as it is in the smaller specimens. 
Several specimens of this species were found in the intestines of 
Cdemia americana.” In these the head was compressed laterally, 
| appearing rectangular in outline when viewed from the front. In cases 
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