CESTODAIIIA 449 



fig. 25), but it may also be pointed (PL 25, fig. 26, c, d) or exces- 

 sively flattened, with a crenulated margin (PI. 25, fig. 26, e) ; 

 when contracted the head becomes transversely wrinkled and 

 oval in transverse section (PI. 25, fig. 27) and more robust 

 (PI. 25, fig. 26, a). In transverse section (PL 25, fig. 27) it is 

 noteworthy that the longitudinal muscle-fibres are disposed 

 into two distinct zones, an outer peripheral zone (sclmus) 

 underlying the subcuticula, and an inner more powerful 

 medullary zone (ilmus), the two zones being widely separated. 

 This condition of the longitudinal musculature (w^hich is 

 equally well-marked in the testicular region) is also found in 

 C . 1 a t i c e p s , and it differs essentially from the single-zone 

 condition of W. virilis and W. acuminata and probably 

 W . m i n u t a . Some transverse muscle-fibres lie immediately 

 external to the medullary longitudinal musculature. In the 

 anterior head region of some specimens I have observed 

 longitudinal thickenings (PL 25, fig. 25) which may be the 

 ' faserzellenstrange ' of Will and Skrjabin. I have not 

 examined them in detail. 



The testicular region is also remarkable, not only on account 

 of its length relative to the uterine region — a feature in Avhich 

 C. filiformis again resembles C. laticeps — but in the 

 fact that the vitellaria throughout the greater part oi this 

 region practically form a ring round the testes, when viewed 

 in transverse section (PL 25, fig. 28). In C. laticeps there 

 is an approach to this annular arrangement, but, judging 

 from Will's figures (27), it is not nearly so complete as in 

 C . filiformis. 



The uterine region (PL 25, fig. 29), as already stated, is very 

 short, the uterus itself being short and but loosely coiled. 

 The uterus opens anteriorly into the vagina from the left side 

 (PL 25, fig. 25, is from the ventral aspect) and the ootype lies 

 on the left side of the ovary, as in W. minuta. The male 

 and female apertures are more separate from each other than 

 is the case in the preceding species, a space of about 25 microns 

 separating the hind border of the male aperture from the anterior 

 border of the female, and this distance is fairly constant. In 



