M. V. Lebour 
353 
about 2 - 6 mm. long and 0‘48 mm. broad. Young rediae are also present 
measuring about 040 mm. long, or, when extended, about 0'60 mm. 
These young redise are very active and move continually by alternate 
contraction and extension. They are quite colourless and transparent, 
have a large muscular oval sucker leading into a strongly developed 
pharynx and an inconspicuous intestine containing no food material. 
(See Plate XXIV, fig. 1.) The anterior end of the body is marked with 
broad wrinkles and this part terminates posteriorly in a “ collar.” At 
the tail end are two blunt processes which disappear in the full-grown 
rediae. The body is full of masses of cells which are evidently the 
beginning of the formation of the cercariae. 
The redia at a later period begins to feed, and, as it grows larger, 
food material is seen in its sac-like intestine as yellow and brown 
granules (black in the figure). The body becomes pinkish or orange, 
the striations, collar and posterior appendages disappear; the shape is 
now simpler and somewhat resembles that of a stocking and the 
creature is very inert (Plate XXIV, fig. 2). Inside the sac are many 
cercarise in various stages of development, and, when full-grown, these 
break out of the redia at the posterior end. 
The cercaria is colourless and transparent and consists of three parts, 
(1) a heart-shaped head, (2) an elongated body, (3) a very active tail, 
not quite so long as the body. The length of the worm minus the tail 
is about 070 mm. The tail lashes continually backward and forward 
and may be occasionally seen detached from the body and moving about 
in the redia. When the worm loses its tail it moves in a leech-like 
manner by means of its suckers. 
The body is covered, except at the posterior end, with minute spines 
and the head bears 29 large pointed spines arranged in an incomplete 
circle. The three last spines on each side are arranged in a peculiar 
way, one large spine occurring between two which are much smaller 
than any of the others. These two spines are on a lower level. 
The oral sucker is at the extreme anterior end and is much smaller 
than the ventral which is situated well behind the centre of the body. 
The mouth leads into a long narrow prepharynx followed by a muscular 
pharynx and a short oesophagus which divides near the centre of the 
body into two narrow intestinal lobes; the latter reach to the posterior 
end of the body. The excretory system consists of an oval posterior 
vesicle into which open two very much branched lateral ducts which 
begin one on each side of the oral sucker, curve gently inwards in a 
small bay and then receive the lateral branchlets. The ducts are 
