bo A FURTHER KNOWLEDGE OF THE CYSTIC CESTODES, 



sucker, is found in the form from Hoplocephalus, and Van 

 Beneden"**" in a form, Milina grisea, from the intestine of Vesper- 

 tilio murinus and serotinus, and which evidently belongs to the 

 genus Piestocystis, describes an unarmed bulb as existing between 

 the four suckers, and also Bellingham,! in a Cysticercus from 

 Cobitis harhatula, has observed a similar unarmed pi-oboscis, so 

 that this character of Diesing no longer holds. The presence of 

 a posterior pulsatile excretory tube and of numerous calcareous 

 corpuscles in the caudal vesicle are features of lesser importance. 



Thus, in the absence of hooks, of a distinctly differentiated 

 body, and of a proper bladder cavity, these forms are sharjily 

 marked off from the Cysticerci properly so-called. 



Returning now to the consideration of the cyst, in Cysticerci 

 properly so-called it is, as already remarked, a wholly adventitious 

 structure, being derived from the tissues of the host and having 

 no genetic connection with the enclosed Cysticercus. In the 

 unarmed forms considered in the preceding, the inner lining of 

 the cyst in that from Hoplocephalus and the inner lining of the 

 cyst, together with the cellular network in the interior of the 

 cyst from Lialis, are, in our opinion, the direct derivatives of the 

 six-hooked embryo, and correspond to the so-called cyst of Mono- 

 cercus arionis and of M. glomeridis, and to the cellular cyst of 

 Monocercus Didymogastris (of. Part ii.), representing in fact the 

 proscolex or " blastogen " of Villot. 



This consideration, viz., that, in the unarmed forms under 

 consideration, we have, surrounding the Cysticerci and forming 

 part of the cyst wall, a part which is the direct derivative of the 

 six-hooked embryo, and which is not found in any Cysticercus 

 properly so-called, is alone sufficient justification for removing 

 them from Villot's genus Cysticercus, and they certainly have no 

 genetic connection either with Echinococcus or Ccermrus. 



* "Les Parasites des Chauves-souris de Belgique," Mdm. de 1' Acad. Roy. 

 de Belgique, T. xl. 1873, as quoted by Moniez, " Essai Monographique sur 

 les Cystiques," p. 144. 



t " On Irish Entozoa," Ann. Mag. N.H. Vol. xiv. p. 398. 



