Dr. O'Bryen BelUngliam on Irish Entozoa. 397 



The head is furnished with four discs or suckers, and a proboscis 

 armed with a double or single circle of recurved hooks; or with 

 two or four depressions, and four retractile armed processes. In 

 the genus Acephalocystis (the lowest in the scale) both head and 

 body are absent, the vesicle or sac alone remaining. 



In none of the Cystic Entozoa have generative organs been 

 discovered, the reproductive power appearing not to be limited to 

 any part of the cyst. Neither has any trace of a nei-vous system 

 been detected in these animals. 



Genus 19. Cysticercus. 

 (Derived from kvgtis, vesica, and KepKos, cauda.) 

 Gen. Char. — Body subcylindrical or flattened, terminating posteriorly 

 in a caudal vesicle. Head provided with four discs and a very 

 short proboscis, which is armed with a double circle of minute 

 sharp recurved hooks. Contained solitarj' in a single cyst. 

 This genus was established by Bloch under the name Hydati- 

 ffera, changed to Vesicaria by Schrank, and to Cysticercus by 

 Zeder, which term has been adopted by Rudolphi and all zoolo- 

 gists. The body of many of the species is marked with trans- 

 verse lines, resembling articulations. The digestive apparatus 

 consists of the four circular oriiices or discs already mentioned, 

 by which they are supposed to absorb the fluid secreted into the 

 adventitious cyst in which they are contained ; from these orifices 

 the absorbed fluids are carried by four slender canals towards the 

 caudal vesicle. 



The species of this genus are almost altogether confined to the 

 mammalia ; Rudolphi enumerates fourteen species, seven or one 

 half of which are doubtful. 



, „ . /• • 7 • * r Cysts in liver of rat (3f MS (/ena«««Ms). 



1. Cysticercus fasciolaris*. < n . ■ ^• c /ht nr j \ 



3 J 1^ Cysts m liver of mouse {Alus Musculus). 



r Cysts in peritoneum covering liver of 



2 tewncoUis < P^S (Sus Scrofa). 



' ' I Cysts in peritoneum covering liver of 

 (^ sheep (Otis Aries). 



* I have only found the Cysticercus fasciotar is in cysts in the liver 

 of the mouse and rat (Mus decumanus) ; much more frequently in the 

 former than the latter. In certain localities they appear to be very 

 rare, and in others very common ; usually but one exists ; the largest 

 number I ever found in the liver of the same mouse was seven ; they 

 were contained in separate cysts, and were of small size. These 

 might readily be taken for a different species from the full-grown 

 specimens, the caudal vesicle being much longer than the body, and 

 the rostellum appearing to be destitute of spines. The shape of the 

 head is also different in some specimens of this species which I 

 possess. 



