P. Manson-Baiir and N. H. Fairley 
39 
All Schistosoma cercariae, whether of the species S. haematobium, S. man- 
soni, or S. japonicum, belong to the furcocerous group of the Distorne cer¬ 
cariae: Leiper emphasizes the following common characteristics of the Bil- 
harzia group of cercariae. 
(1) The absence of the pharynx. 
(2) The presence of a forked or bifid tail. 
(3) The presence of anterior and ventral suckers. 
(4) The absence of eye spots. 
(5) The presence of two or more sets of glands situated posteriorly, one 
on each side of the body, and communicating with the mouth. 
The following measurements for the cercariae of S. mansoni were made 
from 40, and those of S. haematobium from 35, freshly dissected specimens. 
The measurements are as tabulated in Table II below. 
Table II. 
Summary of Measurements . 
Column I 
Cercariae of 
S. japonicum (Leiper) 
1. Total length of body 
and tail 0-25 mm. 
2. Body 0-1 mm. 
3. Breadth of body 0-04 mm. 
4. Post prolongation of 
oral sucker from 
anterior extremity 0 04 mm. 
5. Ventral sucker 
6. Length of tail to 
bifurcation 01 mm. 
7. Breadth of tail 0 01 mm. 
8. Length of each arm 
of fork 0 005 mm. 
). Ventral sucker slightly 
protuberant 
Column II 
Cercariae of 
S. mansoni 
Total length of body 
and tail shorter than 
haematobium 0-374 mm. 
Body, slightly shorter 0-161 mm. 
Breadth of body 0-060 mm. 
Posterior prolongation 
of oral sucker, from 
anterior extremity 0-053 mm. 
Ventral sucker, from 
posterior extremity 0-044 mm 
Length of tail to bifur¬ 
cation, longer 0-213 mm. 
Breadth of tail 0-035 mm. 
Length of each arm of 
fork, shorter 0-066 mm. 
x 0-008 mm. 
No marked protrusion 
of ventral sucker on 
lateral view (vide 
Plate III, fig. 3 a) 
Column III 
Cercariae of 
S. haematobium 
Total length of body 
and tail, longer 0-398 mm. 
Body, slightly longer 0-190 mm. 
Breadth of body 0 064 mm. 
Posterior prolongation 
of oral sucker, from 
anterior extremity 0-073 mm. 
Ventral sucker, from 
posterior extremity 0-049 mm. 
Length of tail to bifur¬ 
cation, shorter 0-208 mm. 
Breadth of tail 0-031 mm. 
Length of each arm of 
fork, longer 0-081 mm. 
x 0-008 mm. 
Marked protrusion of 
ventral sucker on 
lateral view (vide 
Plate III, fig. 4 a) 
Our measurements for the cbrcaria of S . mansoni are larger than those 
given by Faust, Iturbe and Gonzalez, while our measurements of S. haematobium 
cercaria are slightly smaller than the latest given by Faust (June, 1919). 
Regarding the details, see Plate III, figs. 3 and 4. 
The anterior sucker appears to be provided with a number ol papillae 
(about 16), which can be protruded or retracted by muscular action, and which 
