170 TROPICAL MEDICINE AND HYGIENE 



somewhat broad or globular anterior extremity. The 

 oral opening is guarded by two prominent lips, and the 

 body in its anterior half is covered with spinous pro- 

 cesses pointing backwards. Four glands are arranged 

 around the muscular oesophagus and each pair open by 

 a single duct in the adjacent labium. 



Gnathostoma siamense (fig 67). The human species is 

 found only in Siam, and is not a very rare parasite there. 

 It has been found only in subcutaneous tumours, and the 

 worms have been immature. Eight rows of bristles 

 surround the head. The females are 9 mm. by i mm. in 

 breadth. The only male discovered was 5*10 mm. 

 in length by 0*6 mm. in breadth. The male has two un- 

 equal spicules. The cloaca is subterminal, and there are 

 two pairs of pre-anal and two pairs of post-anal papillae. 

 Probably these worms are accidental parasites of man. 

 They are found in the tiger, dogs and cats. 



PHYSALOPTERA. 



Physaloptera have two greatly developed lips, each 

 with two papillae externally, a sharp tooth on the 

 summit* of the lip, and internally a tooth. There is a 

 cuticular collar surrounding the mouth parts. The 

 caudal pouch of the male copulatory bursa is closed 

 and surrounds the tail. There is a series of papillae, 

 usually ten, on this bursa. The vagina opens in the 

 anterior half of the body. The eggs have a thick, smooth 

 outline. Usually parasitic in the intestines of birds. 

 Physaloptera have been found as intestinal parasites in 

 man in East and South Africa, and are described as 

 Physaloptera m or dens. 



Physaloptera mordens. These worms could easily be 

 mistaken for immature round worms. The males are up 

 to 50 mm. in length, and the females 55 mm. They are 

 2 to 3 mm. in breadth. The body tapers slightly anteriorly, 

 and posteriorly more rapidly, terminating in the female in 

 a sharp point. 



