operculum or lid at one end. Opisthorchis pseudofelineus (Fig. 8) 
of cats has an egg 29 to 36 microns long by 14 to 16 microns wide. 
Nematode eggs are very variable in shape and in the amount of 
development at the time they are deposited. Some of the more com¬ 
mon are discussed below. 
Fig. 9. a, b, Toxascaris limbata. Eggs, e. With developed embryo, 
c, d, Belascaris marginata. Eggs. Enlarged as indicated. From Wigdor, 1918. 
In the genus Belascaris, the eggs are more or less globular to 
elliptical, with a thin pitted shell. In B. marginata of the dog, the 
eggs (Fig. 9) are 72 to 104 microns long by 50 to 78 microns wide. 
In B. mystax of the cat, the eggs are more or less oval and 65 to 75 
microns long. 
Fig. 10. Ancylostoma caninum. Eggs in various stages of development, x 300. 
From Railliet, 1893. 
In the genus Toxascaris, the eggs are ellipsoidal, clear and smooth 
in appearance, with an outer clear, double-contoured chitinous shell 
and an inner yellowish membrane with interlaced striations giving 
the appearance of fibres. In T. limbata of the dog and fox, the egg 
(Fig. 9) is 72 to 104 microns long by 64 to 80 microns wide. As 
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