BILHARZIA H^MATOBIA. 



201 



up to the vaginal outlet, wMcli is directly below the lip of the 

 ventral sucker. From BUharz and Leuckart I have taken most of 

 these last-named particulars, since my original specimen from the 

 monkey was a male. I have, however, also been enabled to confirm 

 the truth of many other particulars given above, from a careful 

 microscopic examiaation of the specimens which Leuckart has 

 generously added to my private collection of entozoa. According 

 to Bilharz the aquiferous system is represented by two thin canals, 

 which unite to form a short, tubular " expulsion- sac," anterior to 

 the central point of the tail, where there is probably an open 

 foramen caudate. 



The eggs of BilJiarzia have been very carefully examined, and 

 are rather peculiar. In the first place they are somewhat 

 variable in outline, being usually more or less oval, pyriform, 

 or sharply pointed at the hinder pole, but sometimes assuming a 

 simply oblong figure, in which case they are furnished with a spine- 

 like process placed at the side, and a httle anterior to the hinder 

 end. Between these two type-forms other shght differences of 

 outline also exist, but in all cases, whilst the eggs are still within 

 the uterine canal, the hinder pole (or, in other words, that end of 



Fia. 45. — Eggs and embryos of Bilharzia hcematobia ; a, three ova (X 50 diam.), and a portion of 

 mucous membrane with eggs attached (x 25 diam.) ; h. egg with segmented yelk ; a, free em- 

 bryo ; d, ruptured egg, with embryo escaping (X 150 diam). — John Harley. 



the e^g which is opposed to the one ordinarily provided with an 

 operculum) is directed towards the caudal extremity of the parent's 

 body. Their size is likewise variable, presenting an average longi- 

 tudinal measurement of about ^Js of an inch, and a breadth 

 of ggo'- A true operculum does not appear to exist ; but Bilharz 



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