210 The Philippine Journal of Science 1917 



pouch lies just back of the bifurcation of the intestine and in 

 front of the ventral sucker, and the pouch extends back dorsad 

 to the sucker, being about twice as long as it is wide. In its 

 posterior part is a seminal vesicle, into which the vasa deferentia 

 open. It is capable of considerable distention, so that in some 

 cases it nearly fills the cirrus pouch, while in others it seems to 

 be very small. It opens directly into a muscular cirrus, which 

 is long and spirally coiled and often is extended through the 

 genital pore. 



Female genital organs. — The ovary is globular and is situated 

 a little to the right of the median line at about the middle of the 

 length of the body. Its oviduct passes into a rounded "shell 

 gland," which lies between the ovary and the anterior testicle 

 in the middle line of the body. The vitelline glands commence 

 about midway between the posterior border of the ventral sucker 

 and the anterior border of the ovary. They extend to the pos- 

 terior end of the body. In the anterior part they lie entirely 

 in the lateral margin, but as they pass back, they spread out 

 dorsally and ventrally and almost completely surround the body 

 posterior to the testes. The transverse vitelline ducts turn 

 inward just anterior to the testes and enter the shell gland 

 posterolaterally. A receptaculum seminis is not present. The 

 uterus leaves the shell gland on the left side and turns anteriorly 

 to in front of the ovary, where the coils begin. They fill all of 

 the space in the middle region of the body between the ovary 

 and the ventral sucker. The anterior part of the uterus forms a 

 well-developed vagina, which passes forward dorsad to the 

 ventral sucker and opens at the female genital pore, which lies 

 just to the left of the male pore. 



Ova. — The ova have been well described by Garrison in his 

 paper. They have a thin shell with an operculum at the smaller 

 end and are not segmented when passed in the" faeces. The 

 variation in length and breadth is considerable, but from a 

 measurement of 25 fresh eggs, we get nearly the same average 

 size as Garrison. His measurements are: 



Maximum length, 114.7; breadth, 81.9 microns. 

 Minimum length, 88.8; breadth, 53.5 microns. 

 Average length, 99.58; breadth, 56.04 microns. 



Our measurements are : 



Maximum length, 111; breadth, 74.4 microns. 

 Minimum length, 88.8; breadth, 53.6 microns. 

 Average length, 101.21; breadth, 56.4 microns. 



