The eggs of the following nematodes are somewhat oblong and 
truncated and have tuberculated or pitted shells: Hystrichis tricolor 
(duck; esophagus and proventriculus), 85 to 88 by 36 to 40; Eustron- 
gylides elegans (duck; esophagus and proventriculus), 60 to 70 by 
33 to 38 (Fig. 64); E. tubifex (duck; intestine), 65 to 75 by 44; 
Fig. 64. Eustrongylides elegans. Egg. Enlarged. From Jagerskiold, 1909. 
E. papillosus (duck, goose; esophagus), 68 by 36. 
The eggs of the echinorhynchs or thorny-headed worms of birds 
are elliptical and thick-shelled, similar to those previously described 
for such worms from other domesticated animals. Two species of 
echinorhynchs which occur in the intestine of the duck, goose and 
Fig. 65. Filicollis anatis. Egg. x 340. From Luehe, 1911, after Marval. 
swan are Polymorphus minutus, with eggs 91 to 110 microns long by 
26 to 30 microns wide, and Filicollis anatis (Fig. 65), with eggs 56 to 
60 microns long by 26 to 30 microns wide, according to some writers, 
or 62 to 70 microns long by 19 to 23 microns wide. 
58 
