CESTOIDEA. 7 



worms in man and in the domestic animals belong 

 to two distinct sub-classes, the Taeniae and the 

 Bothriocephali. 



Sub-Class I. — T^ni^. 



These are cestoid worms which have a head 

 (scolex), furnished with four suckers, and frequently 

 with a rostellum, which may be either armed with 

 hooks, or not ; a body (strobile), in the form of a flat 

 band, composed of numerous pieces ; these pieces 

 {cucurhitini, 'proglottides) are either joined together or 

 free, and are provided, when they have become adult, 

 with male and female reproductive organs, which are 

 situated near the margins of the rings. 



Embryonic Condition : — An oval vesicle, or hexa- 

 canthus. 



Larval Condition : — The hydrated or acephalocyst 

 form ; the cystic form {echinococcus, cocnurus, and 

 cysticercus) ; in the greater number of species the 

 larval form is unknown ; the scolex. 



Perfect Condition : — The cucurbitinus or pro- 

 glottis. 



In the larval state taeniae are found exclusively 

 in the parenchymatous organs, or in serous cavities ; 

 in the perfect state they only exist in the intestiaal 

 cavity of vertebrated animals. They are common in 

 the mammiferae and in birds, but are very rare in 

 reptiles and in fishes. 



The cestoid worms belonging to the sub-class of 

 Taeniae are propagated by Alternate Generation ;^ in 



^ Besides the reproduction by means of the genital organs, cer- 

 tain animals are also reproduced by germs; in both cases it may 



