328 AUSTRALIAN ENTOZOA, NO. II., 



developed spermatozoa with small round heads and long tails. 

 The vesicula seminalis is continued as the ejaculatoryduct which 

 traverses the penis to open on the exterior. The vesicula semi- 

 nalis and the proximal part of the ejaculatoryduct are surrounded 

 by a strong muscular sac ; the somewhat considerable space 

 between the walls of the vesicula seminalis and this sac are 

 traversed by muscular and connective tissue fibres which join the 

 walls of each. Between the fibres lie a number of glandular 

 cells representing a prostate gland. 



The male and female ducts open close together into the common 

 genital chamber, which is of some size, and which opens on the 

 exterior on the ventral surface on the middle line and half-way 

 between the two suckers. 



The ovary is an ovoid body of solid appearance lying just 

 anterior to the testes. In the walls of the distal part of the 

 oviduct the shell glands are situated, and this part of the oviduct 

 constitutes the ootype. Into the end nearest the ovary Laurer's 

 canal opens; about its middle the main duct of the- vitelline 

 glands. 



The uterus is a very long and narrow tube which is thrown 

 into a considerable number of folds between the ovary and 

 ventral sucker; skirting the side of the ventral sucker it runs for- 

 wards to open alongside the male opening into the common genital 

 chamber. There is no vagina. The uterus is full of eggs, which 

 are characterised by a very thick chitinous shell. The average 

 longitudinal diameter of the eggs is 0'077 mm., transverse 

 0*062 mm.; the thickness of the shell is 0*008 mm. The eggs 

 consist of the ovum and three or four large vitelline cells. 



The vitelline glands are a number of small, rounded, grape-like 

 follicles which communicate with one another by small ducts. A 

 main lateral duct on each side, about the level of the ovary, opens 

 into a median duct; these median ducts meet together and open 

 into the ootype by a single opening. The follicles are situated 

 laterally, in the middle third of the body, and are grouped round 

 the intestine on each side of the body. The vitelline mass 

 consists of large nucleated cells of an albuminous character. 



