VERMES. 



67 



common Round- Worms living parasitically in man (Ascaris, Stron- 

 gylus, Trichucephalus) belong to this Order. Sometimes they are 

 parasitic in their early stages and later live a free life — such are 



Fig. 47. 



Fisr. 48. 



Fi<?. 49. 



Fig. 47. Diagram of the structure of a Turbellariau : ny, nerve- (cerebral) 



ganglia ; nb, nerve-branches ; yy, yolk-glands ; t, testis ; o, ova ; 



ov, ovary ; c, cirrus ; m, mouth ; ph, pharynx. 

 Fig. 48. Diagram of a Nemertine : b, brain ; m, mouth ; n, renal organs ; 



id, diverticula of intestine ; y, gonads ; sn, side nerve-trunk ; 



pr, proboscis in its dorsal sheath. 

 Fio\ 49. Diagram of the structure of a Nematoid : m, mouth ; ph, pharynx ; 



a, anus ; o, orifice of genital tube. 



Gordius and Mermis. A specimen of a Mantid is exhibited from 

 which half the body of the infesting Gordius has already protruded 

 (fig. 50) . One of the most remarkable Gordii is the great elongated 

 G.fuhjur, or " Lightning Snake," from Celebes. Another very large 



