235 



'20 to '25 mm. from the anterior end, while the second, i.e., 

 that in the vaginal region, occurs at '50 to "60 mm. from 

 the mouth. At *15 mm. from the anterior end, i.e., in the 

 region of the termination of the oesophagus, the body diameter 

 is "08 mm. 



The posterior extremity (fig. 7) is strongly ringed to the 

 tip. The anus lies at about "22 mm. from the termination 

 of the worm, the body width there being about 0'8 mm. 

 Immediately in front of it the diameter is about *1 mm. 

 Behind the anus the body gradually tapers to end in a 

 bluntly rounded tip with a diameter of about '05 to '06 mm. 

 The end of the tail possesses a tiny rounded projection at its 

 termination and there is a pair of very minute papillae situ- 

 ated rather on the ventral aspect in front of it. Joan 

 detected one pair in Argentine specimens, and Neumann 

 figured a pair in the Algerian species. 



The body, except in the anterior region, is marked by 

 well-developed spiral cuticular ridges, which vary in their 

 prominence and closeness of arrangement according to the 

 body region (figs. 18, 19). They are generally from 4 to 6 

 micra in height, but vary in width from 6 to 15 micra. 

 The distances between the spirals increase with the body 

 diameter. Thus, where the latter is about '110 mm. the 

 ridges are about 20 /x apart; when '115 to '120 mm., they are 

 25 to 35 fx apart (figs. 19, 26); '130 mm., 30 to 45 /x apart; 

 '230 to '250 mm., about 60 to 80 /x apart (fig. 25); when 

 *280 mm. (the maximum diameter of the female worm), the 

 ridges are from 95 to about 120 /x distant (occasionally as 

 much as 140 /x) from each other (fig. 18). At 3*5 mm. from 

 the posterior extremity, the body diameter is '26 mm. and 

 the low ridges are '07 mm. apart; at one millimetre from the 

 tip the measurements are '13 and '03 respectively; and at 

 *5 mm. they are '12 and '01 respectively. The ratio of the 

 distance between ridges on the mid-body to the diameter 

 of the mid-body is from '33 to '43. 



The ridges have a slight wavy outline owing to the pre- 

 sence of tiny prominences on them and, at first sight, seem 

 to be arranged in a simple spiral, but they are at least on a 

 great part of the body, apparently along the lateral lines 

 (figs. 18, 19), interrupted in a manner somewhat like that 



Figs. 10 to 12, tail ends of males. 10, 0. gutturosa. 11, 0. 

 lienalis. 12, 0. gibsoni. 13 to 15, heads of males. 13, 0. guttu- 

 rosa. 14, 0. lienalis. 15, 0. gibsoni. 16 and 17, heads of females. 

 16, 0. gutturosa. 17, 0. lienalis. 18 and 19, parts of body of 

 female 0. gutturosa. 18, body width, '270 mm. 19. body width, 

 •120 mm. 20, small spicule of 0. gutturosa. 21, scale to which 

 figs. 10 to 17, 19, 20 were drawn. 22, scale for fig. 18. 



