54 
Bilharziasis 
1. Bilharzia-like cercaria from Planorbis mareoticus (Plate III, fig. 5). 
The measurements of this cercaria were as follows: 
Total length 0-296 mm. 
Body 0-119 mm. x 0-043 mm. 
Tail 0-177 mm. 
Fork 0-044 mm. 
This form differs materially in having a marked and elongated oral sucker, 
armed with numerous and prominent papillae. Pigmented eye spots were seen 
in the specimens collected by Leiper,but were not present in those we examined, 
as perhaps they were too immature. The ventral sucker is round and com¬ 
paratively large. In front of it lie two pairs of salivary-mucin cells; the tail is 
rather broad and provided with short forks. The integument is covered with 
minute spines. The sporocyst is an oblong oval measuring 0-119 mm. by 
0-102 mm. filled with granular germ cells and is easily dissected out from the 
liver substance (Plate III, fig. 6). According to Leiper this cercaria is probably 
the larval form of the Bilharziella of the duck. 
2. Bilharzia-like cercaria from Bullinus dybowski (Plate III, fig. 7). 
The measurements of these cercariae were as follows: 
Total length 0-311 mm. 
Body 0-119 mm. x 0-031 mm. 
Tail 0-192 mm. 
Fork with cuticular expansion 0-150 mm. 
This can easily be distinguished from the true Bilharzia cercaria by its 
narrow elongated head, and very markedly forked tail with its cuticular 
expansions. Each arm of the fork approximates that of the total length of 
the tail. The oral sucker protrudes slightly and is armed with many minute 
papillae; there are three pairs of salivary-mucin cells around the ventral 
sucker, and there is a marked posterior expansion of the oral sucker and a 
rudimentary pharynx. The body and tail are covered with minute spines. 
The sporocysts are elongated finger-like structures (see Plate III, fig. 8), 
apparently emanating from a common centre. In the outer layer of the cyst 
are numerous amber coloured granules. Individual cysts, vary in size, the 
largest measure 0-678 mm. by 0-075 mm. 
This cercaria appears to us to be identical with Cercaria gladii from 
Isodora schakoi of S. Africa described by Cawston and recently figured by 
Faust (1919). Our measurements are, however, smaller than his. 
Both these cercariae differ materially from the fork-tailed cercariae with 
well-marked pharynx, but without eye spots, sent to us by Lt-Col. Glen Liston, 
I.M.S., from Planorbis in India and which has been found to be the larval 
stage of Schistosomum sjnndale of the goat (Liston, 1918). These measure 
about 0-420 mm., total length, and roughly resemble similar organisms figured 
