110 THE INDIAN JOURNAL OF VETERINARY SCIENCE AND ANIMAL HUSBANDRY [ III, I

Length of oral sucker about 1/15 body length; diameter of posterior
sucker about 1/5 body length.................................... P. macaci.

Length of oral sucker about 1/7 body length, diameter of posterior sucker
10/25 body length................................................... P. hawkesi.

The points of difference raised above for distinguishing the three species are
more apparent than real, based as they are on the observation of a limited number
of specimens and the conclusions drawn from them are necessarily fallacious.
With a view to test the validity of the inferences drawn by Fukui data on the
lines suggested by him were obtained from 14 specimens, the result of which is
tabulated below :—

1

2

3

4

5

6

7

Total length of body

5.7

5.2

6.2

5.3

5.3

4.7

5.9

Length of oral sucker/

Total length

0.42/5.7=1/14

0.33/5.2=1/16

0.52/6.2=1/12

0.52/5.3=1/10

0.68/5.3=1/8

0.43/4.7=1/11

0.34/5.9=1/17

Diameter of postorior sucker/

Total length

1.33/5.7= ¼

1.25/5.2=¼

1.38/6.2=1/5

1.32/5.3=¼

1.14/5.3=1/5

0.97/4.7=1/5

1.22/5.9=1/5

8

9

10

11

12

13

14

Total length of body

6.3

6.4

6

6.7

6

6.6

5.8

Length of oral sucker/

Total length

0.54/6.3=1/12

0.52/6.4=1/12

0.53/6=1/11

0.47/6.7=1/14

0.58/6=1/10

0.52/6.6=1/13

0.55/5.8=1/11

Diameter of posterior sucker/

Total length

1.02/6.3=1/6

1.42/6.4=1/5

1.24/6=1/5

1.52/6.7=¼

1.53/6.6=1/5

1.24/6.6=1/5

1.2/5.8=1/5

It will be seen from the above that the ratio of the length of the oral sucker
to the total length of the body varies considerably, i.e., from 1/8 to 117 and that
the one between the diameter of the posterior sucker to the total length also varies,
although within a smaller range. The ratio in the latter case worked out by Fukui
in P. hawkesi is 2/5, which again is far from that existing in the above 14 specimens.
It is therefore suggested that the various ratios worked out by Fukui are not of