106 Parasites of the Zebra 
The head is 0-17 mm. broad, not separated from the body by a con¬ 
striction. 
The mouth is very small and circular, the mouth-collar narrow and 
depressed at the margins (Text-fig. 7, a). 
The lateral papillae are not prominent, the submedian papillae small 
with leaf-shaped terminations. 
The external leaf-crown consists of nine comparatively large almost tri¬ 
angular leaves arising from the inside of the mouth-collar as in Triodonto - 
phorus spp. The elements of the internal leaf-crown are also similar to those 
found in that genus, being septa-like projections, numbering 18 only. 
The mouth-capsule and dorsal gutter (Text-fig. 7, a) are also similar in 
structure to those of Triodontophorus, the former is a little broader than long, 
measuring 0-07 x 0*05 mm. 
Fig. 7. Cratero.stomum tenuicauda gen. et sp. nn. A. Anterior extremity, ventral view, x about 
350. B. Posterior extremity of female, lateral view, x about 125. 
4 
The oesophageal funnel is poorly developed and there are no teeth pro¬ 
jecting from it into the mouth-capsule. The funnel is similar to that found 
in many species of Cylicostomum. 
The oesophagus is narrow and has a length of 0*37-0*4 mm. Excretory 
pore and cervical papillae are at the same level, about 0*25 mm. from the 
anterior extremity. 
The female genitalia are similar to those of some species of Triodontophorus. 
The vagina is very short (Text-fig. 7, b). The vulva opens 0*53-0*57 mm. from 
the posterior extremity; at this level the body has a thickness of 0*2 mm., 
this is reduced to 0*07-0*08 mm. in the anal region, 0*25-0*27 mm. from the 
end of the body. The tail region behind the anus is much attenuated (Text- 
fig. 7, b) and terminates in a point. 
