BILHAEZIA HiEMATOBIA. 199 



Up to the time of Bilharz's announcement of the existence of 

 the Distoma lioematohium, so abundantly found by him in the people 

 of Egypt, almost all the flukes were considered to be hermaphro- 

 ditic, or, in other words, each individual was provided both with 

 male and female organs ; the only exception being that of the 

 Distoma fiUcoUe, regarded by Rudolphi and Dujardin as a species 

 of Monostoma. So common and numerous, however, is the Distoma 

 hcematohium in Egypt, that Bilharz has expressed his belief that half 

 the grown-up people are infested with it ; whilst, in 363 examina- 

 tions of the human body after death, Griesinger found this entozoon 

 present no less than 117 times. The latter authority also conjec- 

 tures that the young of Billiarzia exist in the waters of the Nile, 

 in the fishes which therein abound, or even in bread, grain, and 

 fruit; but I think it is more probable that the larvse, in the 

 form of cercarige, redige, and sporocysts, will be found in certain 

 gasteropod molluscs proper to the locahties from whence the adult 

 forms have been obtained. Our sooty host was, I understood, 

 imported direct from its native country, and was not bred in the 

 Society's gardens ; had it been otherwise, it would not, in all pro- 

 bability, have been infested by Billiarzia. 



The anatomy of Billiarzia has been described by the original 

 discoverer, by Kuchenmeister, and especially by Leuckart; but 

 before entering into particulars I take leave to note, in passing, 

 that it is rather singular that Moquin-Tandon should express his 

 belief that the sexes have been mistaken by such competent 

 authorities. The circumstance of the smaller animal being care- 

 fully described by them as furnished with uterine ducts, containing 

 eggs, ought to leave no doubt in our minds as to the correctness of 

 the generally-received opinion, unless we have distinct evidence to 

 the contrary. Without entering into minute anatomical details, 

 there are several points which demand consideration. Taking the 

 male first, one cannot fail to notice the horseleech-like aspect of 

 the animal, due to the position of the oral sucker, the disk of which 

 is placed almost on the same level as that of the ventral acetabulum. 



