120 



IXVEUTEItUATE ANIMALS. 



time in the waiter ; but tliey finally attach tiienuselves to a blade of 

 grass, and sniround themselves with a horny eaj)sule. If now, the 

 encapsuled embryo should be swallowed liy the sheep, along with 



the grass on which it feeds, 

 the embryo escapes from its 

 horny covering, and makes 

 its wa}' from the stomach of 

 the sheep into the bile-ducts, 

 where it becomes developed 

 into the adult Liver-fluke. 



Order III. Turbellaria. 



The Turbellarian wormf) 

 diHer altogether from the 

 ])recedi]ig orders of .Scolecids 

 in being mostly aquatic in 

 their h.nbits and in being 

 non - par:isitic. They never 

 p )ssess siieking-discs or ceph- 

 adic hiMiks, and their integ- 

 ument is always furnished 

 with vibrating cilia. A 

 water-vascular system is al- 

 ways ]iresent, but it appears 

 .sometimes not to conniiuni- 

 cate with the exterior. The 

 aliment.'uy canal is some- 

 times simjily hollowed out of 

 the tissues and destitute of 

 an aims, as in the Tri'inatodd, 

 and at other times su.sjiended 

 in a free space (body-cavity) 

 and furnished with an anus. 

 It may be sim])le or much 

 brmu-l'ie.l. 



The best known cjf the 

 mcmbcis of this order are 

 cert.-nn little, soft - bodied, 

 o\'ate, r)r i.'lli]itic;d creatures, 

 which ,-ni' connuonly found 

 ire, iir in moist earth, .Mini 

 skin in these curious little 

 with cilia, and also contains 



