20 
Mertens (1892) found the average length of a number of specimens 
to be over 20 mm., and the maximum breadth from 0.7 to 0.9 mm. 
The number of segments varied from 1S<> to 200. and this character 
v’as more or less constant, even with a variation of 3 to 1 mm. in the 
length. 
Miura & Tamazaki (1897) give a length of 20 mm.* and a maximum 
breadth of O.tS to 0.86 mm., measured in the fresh state, 0.3 to 0.56 
mm. after preservation. 
Dujardin (18-15a) gives a length 
of 25 mm., and a maximum 
breadth of 0. 55 to 0. 9 mm. , from 
specimens from rats; Grassi & 
Calandruccio (1887a). a length of 
33 to to mm. : according to Lin- 
stow (1896a). incomplete speci- 
mens measured 23 mm., with a 
maximum breadth of 0.82 mm. 
Head . — The head (fig's. 1. 
6-15) is more or less globular, 
flattened dorso-ventrally, and 
when viewed in front is some- 
what rectangular, with its suck- 
ers at the four rounded angles. 
Its size has been given bv vari- 
ous observers from 215 to t80 // 
in width and 360 to -150 yu in 
length. It is often difficult, how- . 
ever, to tell where the head ends 
and the neck begins, especially 
in certain states of contraction, 
so that it is not always possible 
to determine the length with anv 
degree of accuracy. Examples 
from the rat give measurements 
falling within the limits noted 
above. In specimens both from 
man and from the rat, measured 
in this laboratorv. the head has ranged in width from 130 to 250 /c 
Suckers . — The suckers, globular in shape, measure from 90 to 15u yu 
(Mertens, 1892). In specimens from the rat they seem to be generally 
smaller — according to Dujardin (1815a) 80 yu. and after Linstow (1896a), 
79 yw, in diameter, while we have seen them here, in sizes from 70 to 
90 /^, measured after preservation. In the live worm they are very 
protractile, and may be extruded to a considerable distance (Grassi <fe 
Calandruccio, 1887a). When thus extruded they may be torn away and 
Fig. 12. — Head of K. nana. Enlarged. (After 
Krantz from Kiichenmeister A Ziim, [?18S1] . pi. 5, 
fig. 2.) 
Fig. 13. — Head of H. nana -with protracted rostel- 
lum. Enlarged. (After Krantz from Kttchen- 
meister & Zfirn, [?1881], pi. 5, fig. 3.) 
Fig. 14. — Head of Tstnia murina Dujardin (=H. 
nana). Enlarged. Original type figttre. (After 
Dujardin, 184.5a, pi. 12, fig. A3.) 
Fig. 15. — Head of T. murina Duj. (=if. nana) tvith 
protracted rostellum. Enlarged. Original type 
figure. (After Dujardin, 184-5a, pi. 12. fig. A2.) 
