Onchocerciasis in Cattle and Associated Animals 19 



asymmetrical, their range being as follows : — Eight- preanal 1. 

 par- (or ad-) anal I (or rarely 3), postanal 1, precaudal 1, caudal 

 1 to 2. Left — preanal 1, parannl 3 to 4, postanal 1, preoaudal 1. 

 •caudal 1 to 2. Two unequal spicules of characteristic shape, the 

 longer .207 to .274 (average, .257) mm. long, and .001) to .012 

 (average, .011) mm. in diameter at middle of length, curved in 

 harmony with the body curve, the proximal termination being 

 •enlarged and funnel-shaped, and the distal termination pointed or 

 rarely slightly bifid. Midway the median channel of the distal por- 

 tion of the long spicule opens obliquely forwards and outwards to its 

 surface. Short spicule .08 to .094 (average, .087) mm. long, 

 ■enlarged proximally and flattened somewhat in the greater part of 

 its length, being .006 to .012 (average, .007) mm. in its less 

 -diameter, and .012 mm. in its greater diameter, its distal ter- 

 mination having a shoe-shaped enlargement for the guidance of the 

 long spicule. On one occasion the short spicule was missing, and no 

 evidence could be seen of its having previously been present. 



Female. — May reach at least 100 cm. in length; diameter of 

 central portion of body .38 to .63 (average, .47) mm., tapering at 

 -each extremity, both ends being straight and uninterrupted. 

 Cuticle .02 to .024 mm. thick in the central region, and thickened 

 for greater part of the length of the body into prominent wavy 

 ridges, which may be as much as .138 mm. apart; generally in one 

 -continuous spiral, with occasional gaps at one or other side, and 

 also occasionally a double spiral may be found; no network is 

 present, and the spiral ridges are gradually lost anteriorly and 

 posteriorly; no fine transverse striae could be seen. Mouth termi- 

 nal, with three very small lips and three papillae, but no separation 

 of the head from the body, and no cervical swelling. Oesophagus 

 long, 1.1 to 1.-44 (average, 1.23) mm., and equally thick walled 

 with that of the male, .031 to .034 (average, .032) mm. in 

 diameter. Bulb (or cardia) more frequently indefinite than 

 in the male, but when present is .062 mm. long, and .045 

 to .055 (average, .050) mm. in diameter. Nerve ring at .188 

 mm. from the anterior end; excretory pore not seen. Anus at .125 

 to .232 (average, .187) mm. from the posterior end. Vulva in mid- 

 ventral line, generally on a slight swelling, at .55 to .75 (average*. 

 .63) mm. from anterior end, leading internally into a thick-walled 

 sometimes twisted vagina. Segmented ovum .026 x .017 mm., egg* 

 containing fully developed larvae .0251 to .0329 mm. long, and 

 .0172 to .0251 mm. wide; larvae just free from egg, which has a 

 very thin shell, .12 to .196 mm. long, and .0021 to .0024 mm. in 



3a 



