WORM NODULES IN AUSTRALIAN CATTLE. 327 



Size and Shape. — The male, as would be expected in one of the 

 Filariidae, is not only much shorter, but also considerably thinner 

 than the female. For example, at 0.15 mm. from the anterior end, 

 the male is 0.052 to 0.062 mm., and the female 0.078 to 0.123 mm., 

 and at a distance of 0.5 mm. the male is 0.069 to 0.082 mm., as 

 against the female 0.106 to 0.207 mm., while the average diameter 

 of the male is less than half that of the female, being 0.141 to 0.151 

 mm., as against 0.37 to 0.45 mm. in the female. 



The peculiar shape found to be normal for the female head is 

 not present in the male, even in specimens killed in 70 per cent, 

 absolute alcohol at 65° C, the male head simply tapering to a blunt 

 point. Cleland and Johnston state : " in the male, however, there 

 was no trace of labial structures." Under high magnification and 

 favourable conditions we have seen the three lips, though less 

 distinct than in the female, and in one three very minute papillae 

 were visible, corresponding to those of the female head. 



The Female. — The anterior extremity, 0.5 mm., of the worm 

 tapers more or less rapidly to a usually blunt tip ; sometimes the 

 head is smaller even though the worm is quite mature as seen in the 

 presence of the embryos in the uterus close to the vulva, and the 

 animal is uncontracted, as seen in the structure of the tip. More- 

 over, this anterior end is sometimes seen to be bent slightly ventrally 

 so that the most anterior part of the head is the dorsal lip. As stated 

 by Cleland and Johnston, Park's description of " teeth-like projec- 

 tions and briar-like barbs " on the head end is quite incorrect, but 

 there is a feature of the normal well-preserved head end which shows 

 clearly in four of the six typical cases chosen for tabulation as well 

 as in others. This appears to have been undescribed so far, though 

 it is present in the drawing given of the head in Jour. Roy. Soc. 

 N.S.W., XLIV. (1910), PI. XIV., Fig. 1. 



The extreme tip is separated from the rest of the head by a 

 fold and depression of the cuticle and dermis {see fig. 5), giving it 

 the appearance of a half moon set in to the wider main part of the 

 head. Cleland and Johnston state in their original description of 

 the new species that " the head is not constricted from the rest of 

 the body." The length of this terminal postion is 0.0132 to 0.0136 

 m.m., and it is present in specimens A, D, E, F, though not so well 

 defined in the specimen D. In the other two cases the head is 

 lacking in this respect {compare fig. 6), the absence of the fold being 

 almost certainly due to some contraction in these cases. At least 

 two of those specimens in which this feature appears were fixed in 

 70 per cent, alcohol, at 65° C, and were excellently preserved, so 

 that there can be no doubt that this is the normal state of the head 

 end. As stated by Cleland and Johnston, " the mouth is small, 

 rounded, and terminal, and appears to be surrounded, in the female, 

 by three slight projecting lips." The lips, which are very small, can 

 only be seen immediately around the mouth opening, and are some- 

 times almost indistinguishable, even in the female. Papillae can be 

 detected only occasionally, and then show under high magnification 



