156 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



Male 2.5 to 3.5 mm. long, with a maximum thickness of about 80 fx 

 (fig. 201). Head about 25 /t in diameter. Esophagus frequently bent 





i/iomm 



Fig. 201.— Heligmosomum 

 vexillatum. male. 



Fig. 202.— Heligmosomum vexillatum. Bursa, dorsal 



VIEW. 



or sinuous to some extent and about 250 /a long and 30 \x. thick near 

 the posterior end in a small specimen. The nerve ring is about 110 ju 



from the anterior end of the body. 

 The intestine is straight. The 

 bursa is set on at approximately 

 right angles to the long axis of the 

 body and has a spread width equal 

 to more than three times the maxi- 

 mum thickness of the body (fig. 

 202). The body terminates pos- 

 teriorly in a cone which projects 

 central of the bursa (fig. 203). 

 The arrangement of the bursal rays 

 is that given in the generic diag- 

 nosis. The tips of the externo- 

 dorsal and postero-lateral ra3^s are 

 fairly close together ; at an interval 

 from this are the medio-lateral and 

 externo-lateral rays, with their tips 

 not so close together; and at a less 

 interval is the latero-ventral ray, 

 with its tip still farther removed 

 from the ventro-ventral ray than 

 was the case with the two pre- 

 ceding related pairs. The dorsal 

 ray is about 65 i*. long and the 

 spurs nearest the proximal end originate about one-third of the dis- 

 tance from the base to the ends of the ray. The main branches 



Fig. 203.— Heligmosomum vexillatum. Pos- 

 terior extremity of male, ventral view. 

 d., Dorsal lobe and ray; e. A., externo- 

 dorsal ray; e. I., externo-lateral ray; 

 I. v., latero-ventral ray; m. I., medio- 

 lateral ray; p. I., postero-lateral ray; 

 V. v., ventro-ventral ray. Enlarged. 



