— 109 — 



with their tips backwards; the length of the spines attains 

 0,029 — 0,030 mm. The spines cover tlie entire surface of the 

 body, the hinder part of it not excepted. 



Tlie suclcers are strongly developed.. The oral sucker may 

 be 0,289 mm. in length, with a width of 0,314 mm. And 

 again, contrary to what we find in the other species of Pro- 

 sthogonimus, the width of the oral sucker in our parasite 

 is greater than its length. Tlie nearly spherical pharynx, 

 0,22 mm. long and 0,238 mm. wide, passes into the oesopha- 

 gus which attains 0,29 mm. in length. The blind ends of the 

 intestine which is filled with a black substance (food) run 

 beyond the posterior margins of the testes, not reaching, 

 however, the posterior end of the body. 



The ventral sucker is situated on the border of the ante- 

 rior and middle third of the body-length, being 0,85 mm. 

 long and 1,0 mm. wide. 



The oval testes are situated in the middle third of the 

 body at the same level, being divided from each other by 

 the convolutions of the uterus. 



The bursa cirri is of an original retort-like shape, its bottom 

 reaching the point where the oesophagus divides into the 

 intestinal trunks; the length of bursa cirri is — 0,883 mm. It 

 opens to the exterior by the male genital aperture which is 

 situated in the left half of the body near the opening of the 

 oral sucker, between the latter and the aperture of the female 

 genital apparatus. 



The ovary is multilobed, clustershaped, and is situated 

 nearly medially, both posteriorly and dorsally to the ventral 

 sucker. The vitelUne glands, which are situated near both 

 lateral margins of the body, begin at the level of the middle 

 of the distance between the anterior edge of the ventral su- 

 cker and the bifurcation of the intestine, and end somewhat 

 anteriorly to the blind ends of the intestinal branches. In some 

 specimens an asymmetrical arrangement of the vitelline glands 

 has been observed: on the right they were more developed 

 than on the left side. The vitelline glands consist of extremely 

 small follicles which are not clustered into groups, as it is 

 observed in the species Prostliogonimus pelliicidus Linst., 

 1873 and P. putscJcowskii Skrjabin 1912. The length of 

 the right vitelline gland in the specimen drawn by me reached 

 3,06 mm., and that of the left — only 2,04 mm. 



