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there are seven others that have apparently no settled place, 

 and are called particular types. 



The first order, the Turbellaria, are recognized by vi- 

 bratile cilia covering their bodies, which are composed of soft 

 tissue, and are of various forms : some flattened, pear-shaped, 

 others cylindrical, of enormous length, and jointed somewhat 

 like tapeworms ; they are capable of increase by the usual 

 sexual methods and by fission. 



The second order, the Trematoda, or Flukes, have soft 

 roundish or flat bodies enveloping the visceral organs. They 

 are small animals, the smallest being about one-hundredth 

 part of an inch, and the largest varying from one to five inches 

 in length. They undergo several metamorphoses, the earlier 

 of which take place in ponds, or ditches, and damp pasture- 

 grounds. 



The common liver fluke {Fasciola or Distoma hepatica) 

 gives rise to a disease called " the rot," in sheep ; it is oviparous, 

 and the action of water loosens the lid-like covering that the 

 egg is provided with, and sets free a little wedge-shaped 

 embryo covered with cilia. After a short active life it alters 

 its form, and takes up its abode in some mollusc, where it 

 becomes transformed into a cyst, and afterwards develops into 

 a tadpole-like animal called a Cercaria^ which, if swallowed 

 by cattle, make their way to the liver, and after a time become 

 converted into sexually mature Trematoda. Again they get 

 restless, make their way to the intestinal canal, and eventually 

 become expelled with the faeces. 



Mr. West then went on to describe the anatomy of one 

 of the DistomidcE which infest man ; and called attention to 

 one of the particular types, Bilharzia, which at first sight 

 has the appearance of a round worm or leech. This resem- 

 blance is due to the edges being rolled inwards, forming a 

 tube, as it were, in which the female is generally found em- 

 braced. She is a small filamentous-looking body, not nearly 

 so large as the male. Bilharzia are found mostly in Egypt, 

 and give rise to many serious complaints. 



The third order, the Nematoda, or round worms, are of 



