P. M anson- Baiir and N. IT. Fairley 55 
by Cawston (1915, 1917) as occurring in Physopsis africana, though his figures 
lack accuracy and detail. The measurements of this Indian cercaria we 
procured are as follows: 
Total length 0-420 mm. 
Body 0-162 mm. x 0-047 mm. 
Tail 0-260 mm. 
Fork 0-092 mm. x -021 mm. 
For the purpose of comparison, and to aid future workers, a short descrip¬ 
tion is given of other cercariae found in Bullinus, Planorbis and a few other 
common species of fresh-water snails in Egypt, as figured in Plate III. 
Plate III, fig. 9. Cercaria, cellulosa, a microcotyledonous distome cercaria (spec. inq. Looss, 
Rech. sur la faune parasii. de VEgijpte, p. 227, PI. XIV, figs. 159,161). Small, hyaline, very active 
and found in 10 % of Cleopatra bulimoides from Tel-el-Kebir. Looss found them also in Melanio 
tuberculata. 
The anterior sucker is provided with a hyaline dart. Opening out into it are two pairs of well- 
marked cephalic glands. The ventral sucker is round, and is situated immediately posteriorly to 
the central line of the body; laterally placed to it, are collections of genital cells. The excretory 
vesicle is apparent in the posterior part of the body. The sporocysts are round, or sacciform (Fig. 
10) and are unpigmented. 
Plate III, fig. 11. Microcercous distome cercaria found commonly in liver of Limneae (mostly 
L. caillaudi and I. truncatula) resembles Cercaria pusilla spec. inq. of Looss, shows two pairs of 
cephalic glands with ducts opening into oral sucker, a muscular pharynx and well-marked ventral 
sucker. Excretory bladder situated at the posterior part of the body, and two excretory canals 
opening into corresponding vesicles. In the oral sucker is situated a hyaline dart. 
Plate IV, fig. 1. Under this heading are included probably amphistome cercaria of three species 
as described by Looss. They are of a large size, about 0-84 mm. in length, by 0-427 mm. in breadth. 
The body is oval and almost circular, and in the more mature forms is so darkly pigmented that no 
details of structure can be made out. They resemble indeed, both in size and movements, minute 
tadpoles. They are found most commonly in Bullinus —about 5 %, but were occasionallv seen in 
Planorbis botssyi also, as well as in Limnaea caillaudi and Cleopatra bulimoides. The pigmentation 
of the body seems to commence from two eye spots situated in the anterior third of the bodv and 
thence to radiate along the excretory and alimentary canals till the whole body is thus pigmented. 
The anterior sucker is round and smaller than the posterior, which is also circular and muscular, 
and is situated at the extreme posterior end of the body. The oral sucker leads into a muscular 
oesophagus, and eventually into a semicircular branched alimentary canal. The excretory system 
is represented by a series of retractile globules passing in a circular manner from the anterior to the 
posterior sucker. 1 he tail is elongated and tapering. These cercariae are probably larval stages 
of Gastrodiscus aegyptius (Cobbold) of the horse, of Gastrothylax gregarius (Looss) and of Amphisto- 
mum conicum (Rud.) from the stomach of the buffalo. 
Plate IV, fig. 2. Mature redia of Fig. 1; surprisingly small considering the size of the cercariae. 
They are obtuse oval in shape and hyaline without any protrusion or appendix and measure 
0-77 mm. by 0-13 mm. and show large germinal masses in their cavity. At the posterior pointed 
extremity there are some well-marked germiniferous cells. 
Plate IV, fig. 3. This is a monostome cercaria, the Cercaria pleurolophocerca of Sonsino 
(1895) and Looss (1896). We found it occurring in Melania tuberculata, both from el Marg and 
Tel-el-Kebir. Its total length is 1 00 mm. The body is 0-27 mm. by 0-08 mm. The tail is 0-49 mm. 
in length and is provided with a lateral cuticular expansion. In shape the body is an elongated 
oval tapering towards the anterior sucker. The cuticle is clothed externally by a number of minute 
