54 VURMES. 



then it surrounds itself with a cyst, and a vesicle containing a 

 fluid is developed ; it is now called a " scolex." These cysts were 

 also known as " hydatids." 



" When ova of the pork tape-worm (Tosnia soliitm) gains access 

 to the alimentary canal of a pig, their shells become digested, and 

 the enclosed six-hooked embryos escape and bore their way into 

 the circulation. Thence they proceed to the cellular tissue and 

 become transformed into measles (Cysticercus celluloses). In the 

 sheep the cystic worm of the brain (Ccenurus cerebralis), which 

 causes the ' gid ' or ' staggers,' becomes the Tcenia coenurus of 

 the dog. The Cysticercus pisiformis, or pea-measle of the rabbit, 

 is the scolex of Tcenia serrata infesting the dog. The Cysticercus 

 fasciolaris of the mouse becomes the Tcenia crassicollis of the cat. 

 The common hydatid (Echinococcus vetcrinorum) becomes the Tcenia 

 echinococcus of the dog. The slender-necked hydatid (Cysticercus 

 teniuicollis) of the sheep becomes the Tcenia. marginata of the dog. 

 The Cysticercus talpce and C. longicollis infesting moles become 

 respectively the Tcenia tenuicollis and T. crassiceps of the fox. 

 Lastly, a scolex called Staphylocystis micracanthus, which is found 

 in a myriopod (Grlomeris), is the larval state of Tcenia pistillum 

 infesting shrews (Sorex)." [Dr. Cobbold in lit.} 



The chain of reproductive joints or zooids is called the " stro- 

 bila." Each new joint is formed between the head and the next 

 joint ; the most distant joints are therefore the oldest. 



The Cestoda are sometimes combined with the Trematoda and 

 the Turbellaria to form the class Platyelmintba ; or the two 

 former only are combined to form the class Cotylidea. 



According to Cobbold, there are about 260 species belonging to 

 the Cestoda. 



Tceniidce. Diphyllidce. Tetrarhynchidce. 



Tsenia (Tape-worm). Echinobothrium. Tetrarhynchus. 



Dibothriidce. Tetraphy Hides. CaryophyllceicJce. 



Dibothrium. Phyllobothrium. Caryophyllzeus. 



Eothriocephalus. Acanthobothrium. Eustemma. 



Ligulidce. 

 Ligula. 



Class II. NEMATELMINTHA. 



Body more or less cylindrical or thread-shaped, without true 

 segments, and without limbs. Mouth anterior, often furnished 

 with hooks or papillae. 



