144 



TROPICAL MEDICINE AND HYGIENE 



bent back in both sexes, and in the male the copulatory 

 bursa is not median but directed to one side. The oral 

 capsule is smaller and rounder in N. americanus (fig. 63, 

 A and B). 



B 



A B 



FIG. 64. A, A, head and tail of male, Ankylostomum dttodenale ; B, B, 

 head and tail of male Necator americanus; x, x, dorsal rays. 



When examined closely more important differences 

 are found. The armature of the buccal capsule consists 



