C. L. Boulenger 
151 
about 15 fi in breadth and is provided with six small papillae. The 
oesophagus has a length of 270/x, the intestine is multicellular and the 
genital rudiment no longer exists as a lens-shaped body. The most 
interesting organ at this stage is the tail, which retains all the character¬ 
istic larval features, namely the forked extremity and the rod-like 
terminal process. 
The first traces of external sex characters were seen in specimens 
2-5 mm. in length, these very closely resemble the earlier stage just 
described and do not show any appreciable increase in breadth, in a few 
Fig. 4. Young stage from intestine of lamb. a. anus. i. intestine, on. oesophagus, x 100. 
Fig. 5. Posterior end of similar but slightly older stage from intestine of lamb. a. anus. 
i. intestine, x 300. 
individuals however a distinct swelling is visible, just anterior to the 
tail-fork and at about the level of the anus, which probably represents 
the first sign of a male bursa. 
The bursal rudiment is much more conspicuous in a specimen 
3-3 mm. long, here it forms a hollow swelling about 60p broad in the 
same position below the larval skin, the latter is very loose in the 
anterior part of the body and is evidently about to be cast; this is 
probably the final moult before the adult stage is reached. In this 
specimen the body has an almost uniform thickness of 50p, tapering 
however at the two extremities but only slightly posteriorly, the region 
10—2 
