46 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50 



Male 6.4 to 9.85 mm. long and with a maximum thickness of about 

 260 /*. There is a well- developed bursa (figs. 51 and 52) which origi- 

 nates anterior of the preanal sucker. It is sustained in the anal 

 region by three pairs of papillae and is notched at the distal termina- 

 tion of the third of these. The bursal lobe originating at this notch 

 is a small one, the bursa abruptly diminishing in diameter just 

 behind this pair and being continued as the terminal portion 

 accompanying the tail proper. This last portion is sustained by 

 three pairs of papillae and extends to the tip of the acutely pointed 



HO mm. 



'lyiomm.' 



Fig. 51.— Heteeakis spumosa. 

 postekioe extremity of 

 male; ventral view. 



Fig. 52.— Heterakis spumosa. Pos- 

 terior EXTREMITY OF MALE; LAT- 

 ERAL VIEW. 



tail. Of the three pairs of papillae sustaining the bursa in the anal 

 region the anterior pair is much the largest. The proximal portion 

 appears to be thick and granular, the diminished distal portion is 

 thin and clear. The next pair of papillae behind this is shorter and 

 has the same structure, a granular proximal portion and a clear dis- 

 tal portion. The next pair of papillae, that in relation with the 

 bursal notch, does not show this same structure; it is longer than 

 the preceding pair. Of the three pairs of papillae sustaining the 

 bursa along the tail proper the anterior pair is the thinnest, the 

 middle the thickest, and the posterior pair is intermediate in thick- 

 ness. These are all of about the same length. It is sometimes diffi- 



