48 PROCEEDINGS OP THE NATIONAL MUSEUM vol. 81 



two lateral groups of three, each containing a protrusible fingerlike 

 proboscis. The excretory pore is situated in the floor of the 

 proboscid chamber; excretory vesicle large and branched, each of 

 the branches becoming narrowed into 1 of the 4 chief trunk vessels, 

 2 of the vessels being median and 2 lateral. The lateral vessels ex- 

 tend anteriorly, lateral of testes, and unite immediately anterior and 

 ventral of the intestinal bifurcation; they are provided with short 

 lateral branches along their course from the level of the anterior 

 margin of the testes to the level of the intestinal bifurcation. The 

 two median vessels pass between the testes and extend anteriorly in 

 the intercecal field to near the intestinal bifurcation where they 

 terminate blindly. Genital aperture near right margin of oral 

 sucker. Cirrus pouch long and slender, its posterior end lying in 

 the median line about one-fourth of the body length from the an- 

 terior end; it contains a small portion of the seminal vesicle, an 

 ejaculatory duct surrounded by prostate cells, and a muscular cirrus. 

 Testes deeply lobed, about 2 mm long by 940ju, wide, situated in the 

 same transverse plane near the junction of the third and last body 

 fourths; they are so situated that their long axes are oblique to the 

 long axis of the body, their bases being separated by the intestinal 

 ceca. The vas deferens is expanded to form a relatively wide semi- 

 nal vesicle which extends anteriorly in a more or less tortuous course 

 from the level of the anterior margin of the testes to the cirrus 

 pouch. Ovary oval, 890/* long by 5T0/A wide; Mehlis's gland 820/a 

 long by 490/A wide, situated to the right of ovary; both ovary and 

 Mehlis's gland lie in the angle formed by the testes. There is no 

 seminal receptacle or Laurer's canal. Vitellaria extracecal and post- 

 testicular in position, and consisting of grapelike groups of oval 

 follicles, each lateral mass being composed of about 50 groups. 

 Uterus long and slender, composed of numerous, closely packed 

 transverse loops which extend laterally beyond the limits of the ceca 

 as far as the lateral branches of the excretory system. Eggs 26/x 

 long by 15/jt wide, thin shelled, and with a long filament at each pole. 



Host. — EaUcore dugong. 



Location. — Intestine. 



Distribution. — Australia (coast of Queensland). 



Family OPISTHOTREMATIDAE Poche, 1926 



Family diagnosis. — Body spoon shaped; ventral surface spiny. 

 Esophagus moderately long, slender; intestinal ceca without diver- 

 ticula. Excretory pore dorsal; excretory vesicle short and with lat- 

 eral branches. Genital openings median and situated almost at ex- 

 treme posterior end of body. Cirrus pouch long and slender, median, 

 containing a strongly convoluted seminal vesicle and a protrusible 



