58 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 50. 



i/io mm. 



fey*. 



buccal cavity is simple and shallow. The esophagus is club-shaped, 

 gradually thickening posteriorly and terminating in a bulb. The 

 bulb is often deeply set in the dilated enfolding anterior end of the 

 intestine. The prominent cervical alae 

 start at the base of the lips and swing 

 around toward the ventral surface 

 (fig. G5). 



31ale 2.786 to 4.47 mm. long and 140 

 to 170 [J. thick in front of sucker. Head 

 diameter about 65 [x. The esophagus, 

 exclusive of the bulb, is about 355 to 515 

 [x long and 50 to 70 \i thick. The bulb 

 is 136 to 172 \i long and 112 to 145 [x 

 thick. Nerve ring 130 jji, from head end 

 in one specimen. The bursal membrane 

 is very slightly developed. Most of the 

 caudal papillae (fig. 66) are clustered 

 about the cloaca 1 aperture, a single pair 



holding an iso- 

 lated position 85 



to 112 [JL from 



the tip of the 



tail. The clo- 



acal aperture is 



about 235 ^ 



from the end of 



the tail. Here 



is a line of 6 



adanal papillae, 



two outer larger 



ones and two 



smaller ones 



f f'nar^ 



Fig. 6C.— Heteroxynema cucul- 

 LATUM. Posterior extremity 



OF MALE. 



1/20 mm. 



just median of 



each of these. 



Just posterior of 



these papillae is 



a pair in the 



submedian posi- 

 tion, followed 



directly by an 



unpaired papilla in the median line. No preanal papillae have been 

 observed, the total number of papillae present being 11. There are 

 no spicules present. The sucker (fig. 67) has a delicate longitudinal 

 and transverse sculpturing which gives the effect of fenestration. 



Fig. 67.— Heteroxi'nema cucul- 



LATUM. Anal SUCKER OF MALE. 



