NO. 9 cuckler: nematode parasites 147 



rounded rather than truncate cephalic region, the absence of cuticular- 

 ized structures on the anterior end of the esophagus, the differences in 

 the genital papillae, and the longer spicule. 



Alaeuris labicula, new species 

 (Plate 14, figs. 15-21) 



This species of Alaeuris composed about 10 per cent of the entire 

 collection. 



These are medium-sized oxyurids. The length of the male (fig. 15) 

 varies from 3.11 to 3.45 mm., with an average of 3.28 mm. The maxi- 

 mum body width is from 0.19 to 0.26 (average 0.24) mm. The size 

 of the mature female (fig. 16) ranges from 5.51 to 6.08 (average 5.34) 

 mm. in length by 0.44 to 0.53 (average 0.47) mm. in wndth. 



The cuticula is thick and has distinct transverse striations about 

 0.005 mm. apart. There are no lateral or cervical alae, although the 

 male has wide caudal alae. 



The anterior end of this species is bluntly rounded, and the cephalic 

 region (fig. 17) is indistinct. The lips are inconspicuous. The mouth is 

 terminal and triangular in shape; it is surrounded by three lips which 

 are best seen en face view. In some specimens examined a slight inden- 

 tation about mid-way between the corners of the mouth could be seen 

 on the anterior margin of each lip. It was considered at first that this 

 perhaps indicated a slightly bilobed condition of the lips, but when 

 other specimens were examined the same condition was not found. 

 There is apparently a slight variation in the lip margins but the lips 

 are never distinctly bilobed. 



There are eight cephalic papillae and two amphids. The amphids 

 are conspicuous. They terminate near the posterior margins of the 

 ventrolateral lips. The papillae are arranged in two circles, each con- 

 taining four papillae. The papillae in the outer circle are larger than 

 those of the inner circle. Two of the outer circle papillae are arranged 

 on the dorsal lip, opposite the dorsal corners of the mouth. The other 

 two external circle papillae are on the ventrolateral lips, and are located 

 lateral to the ventral corner of the mouth. The internal circle papillae 

 are situated on the ventrolateral lips. The papillae are arranged in an 

 unusual manner, as they seem to show bilateral symmetry, rather than 

 radial symmetry, as might be expected from the radial arrangement of 

 the lips. 



