WORM NODULES IN AUSTRALIAN CATTLE. 329 



large and generally well separated, but may be much smaller and 

 almost touching in the middle line. The middle post-anal pair are 

 of fair size, and do not appear to show much variation. The 

 posterior post-anal papillae are situated almost oi the extreme 

 posterior end, and although smaller than the others are generally 

 very clear. 



In the female the tail is more bluntly pointed than in the male. 

 The anal opening (fig. 8a) lies at a distance of 0.207 mm., or in a 

 less perfect specimen apparently 0.175 mm. from the extremity of 

 the tail ; the usual thickness of the body at this level being also 

 0.207 mm. 



Cuticle. — As already described, the cuticle is raised up into one 

 or sometimes two series of spiral ridges, each more or less irregular. 

 Even in extreme cases these ridges only extend as far forward in 

 the female as 0.34 mm. from the anterior end, while behind the 

 anus there is practically no such ornamentation. No transverse 

 striations of the cuticle have been seen, nor any longitudinal stria- 

 tions other than those due to the longitudinal arrangement of 

 the muscles. In the male the spiral ornamentation is naturally 

 much finer and less marked in character. 



Internal Structure. 



Owing, perhaps, to the conditions of pressure, etc., under 

 which the worm lives, many details of its structure are extremely 

 difficult to decipher, more especially as will be seen in connection 

 with the nervous and excretory systems, which show an asymmetry 

 and irregularity which is quite evidently a characteristic of the 

 worm, independent of methods of fixation, preparation, etc. 



Digestive System. — In the male the oesophagus is straight, and 

 is 0.65 to 0.72 mm. long and 0.0155 mm. wide, that is, somewhat 

 narrower than the female. Sometimes slight swellings are present 

 on the oesophagus, just before it enters the intestine, but no definite 

 " cardia," like that of the female, could be found in any instance. 

 The long, straight, intestine passes back to the cloacal opening, 

 and, though much reduced, is similar to that of the female. The 

 spicules will be described in connection with the reproductive 

 system. In the female the long narrow oesophagus, sometimes 

 straight, sometimes twisted (figs. 5, 6, and 7, and 35), varies from 

 0.52 to 0.92 mm. in length, and is 0.02 mm. in diameter. Just 

 before it enters the intestine the globular "cardia," already described 

 by Cleland and Johnston, is always found, though not always- 

 clearly distinguishable. The position of this cardia, measured 

 from the anterior tip of the head, is seen to be at 0.57 to 0.86 mm., 

 and has no invariable relationship to the position of the vulva, as 

 affirmed by Cleland and Johnston. The extreme length and 

 diameter of this cardia is usually 0.031 mm., though in specimen B, 

 in which it was distended by a number of refractive granules, it 

 was 0.069 mm. long by 0.04 mm. wide. The apparent condition 

 of the junction of oesophagus and intestine varies naturally with 



