o 
H. A. Baylis 
longitudinal nerve. It is club-shaped, as in the othei species, and expands 
towards its inner end to a maximum width of 0-025-0-03 mm. It is almost 
completely filled by the internal seminal vesicle. There is also a pear-shaped 
external seminal vesicle (Fig. 3, v.s.e.), which occupies the space between the 
inner end of the cirrus-sac and the ovary. V entrally to this lies a large re- 
ceptaculum seminis (Fig. 3, r.s.), being the expanded inner end of the vagina, 
which runs along the ventral side of the cirrus-sac. 
The passage from mature to gravid segments is very gradual. The latter 
are almost completely filled by the sac-like uterus, which contains a large 
number of ova. These have a thin outer membrane and a thicker, chitinised 
inner shell, between which there is a rather deeply-staining granular material 
which sometimes appears to form a third membrane.” The inner shell is dis¬ 
tinctly lemon-shaped, as opposed to the almost spherical inner shell of H. nana 
and H. nana fraterna, and it possesses at or near each pole a well-developed 
thickening. The terminal filaments present in the other species appear 
to be absent. Measurements taken by Mr Dudgeon and Dr A. C. Stevenson 
from ova in a fresh state in the faeces of infected rats were as follows: 
outer membrane, 49-60 /jl x 42-48 ju.; inner shell, 28-5-35*25/x x 22-5-28-.) p,, 
the knobs at the poles measure 2-4/x; onchosphere, 24-35/x x 21-27/x; 
length of embryonic hooks, 10-5-15/x. 
The following table of measurements and other data taken from Mi 
Dudgeon’s material will help to bring out some of the differences between 
H. nana J rater na and the new species. 
Total length 
Width of strobila (max.) 
Width of scolex (great varia¬ 
tion according to degree of 
contraction) 
Suckers, outside diameter 
Rostellum, diameter 
Number of hooks 
Length of hooks 
Number of segments 
Segment at which rudiments 
of genital organs begin to 
appear (roughly) 
Segment at which mature geni¬ 
tal organs appear (roughly) 
Number of gravid segments 
(roughly) 
Ova, diameter of outer mem¬ 
brane 1 
Ova, diameter of inner shell 1 
Ova, diameter of onchosphere 1 
Embryonic hooks, length 
II. nana fraterna 
Up to 20 mm. 
0-27—0-51 mm. 
010—0-23 mm. 
Mean about 019 mm. 
0-05—0 07 mm. 
0 05—0 07 mm. 
22—20 (usually 22 or 23) 
16-18yU. 
Up to 250 
35th 
75th 
20—70 
07-5—90/a x 00—87/x 
40-5—51m x 30—43-5 /a 
30—45/a x 31*o—40-5 /a 
15/a 
H. longior 
Up to 45 mm. 
(00 mm. if stretched) 
0-42—0-53 mm. 
(0-05 mm. if contracted) 
0-21—0-20 mm. 
Mean about 0-24 mm. 
0-075—0-093 mm. 
0-07—0-08 mm. 
21—22 (usually 22) 
19—20/a 
Up to, or over, 000 
50th 
250th 
00—100 
49—00/a x 42— 48/a 
28-5—35-25/a x 22-5—28-5/a 
24— 35/a x 21— 27/a 
10-5— 15/a 
1 These measurements were taken by Mr Dudgeon and Dr Stevenson from fresh ova in the 
faeces of rats. 
