established in the case of some worms. Haemonchus contortus is so 
commonly present that the presence of eggs falling within the size 
range for this species may be taken as a fairly safe indication that this 
worm is present. 
The egg sizes in microns for some of the larger strongyles, those 
having a well developed mouth capsule and belonging to the family 
Strongylidae, are as follows: The cattle hookworm, Bustomum 
phlebotomum, 75 to 98 long by 40 to 50 wide; the sheep hookworm, 
Bunostomum trigonocephalum, 75 to 83 long by 38 to 45 wide; the 
cattle nodular worm, Proteracrum radiatum, 75 to 85 long by 40 to 50 
wide; the common sheep nodular worm, Proteracrum columbianum, 65 
Fig. 36. 
Trichuris ovis. Eggs. 
Enlarged. From Fiebiger, 1912, after Csokor. 
to 75 long by 40 to 45 wide; the goat hookworm, Proteracrum asperum, 
reported from the Canal Zone, 83 to 85 long by 55 to 60 wide; the 
veined nodular worm of sheep, Hysteracrum venulosum, 85 to 90 long 
by 45 to 55 wide; the sheep and goat nodular worm, Gaigeria pachyscelis 
(Fig. 34), reported from India and the Belgian Congo, 105 to 118 long 
by 50 to 55 wide; the strongyle from the large intestine of ruminants, 
Chabertia ovina, 90 to 100 long by 50 wide. 
The egg sizes in microns for some of the trichostrongyles, which 
are the smaller strongyles, those without a well developed mouth 
capsule and belonging in the family Trichostrongylidae, are as follows: 
39 
