152 



ENTOZOA. 



connected with or prolonged into a series of fibres forming the so- 

 called pharynx. As far as my own observations extend this special 

 muscular development corresponds with the oesophageal bulb, which 

 in other trematode species is often entirely removed from its con- 

 nection with the oral sucker, and consists of two sets of fibres as 

 obtains in the sucker itself. Mr. Simonds, however, only recognizes 

 one set of fibres, and says that "these fibres run lengthways by 

 the side of the (oesophageal) tube, reaching from its upper to its 

 lower part, and so embracing it as to form an elongated sphincter." 

 My own observations appear to be borne out by the independent 

 and earher inquiries of Mr. Busk, from whose drawings the accom- 

 panying figure is selected. The sucker here figured is taken from 



Fig. 33.— The oral sucker of a small species of fluke (x 220 diam.). — Busk. 



a different species of trematode, but in all essential features it is the 

 same as that of Fasciola hepatica. The radial fibres when viewed 

 fi'om above display a cellular appearance, the individual fibres being 

 seen, as it were, in transverse section. 



As before remarked, these suckers are both employed as organs 

 of locomotion, but the lower one also undoubtedly serves as an 

 anchor or holdfast. The oral disk will also materially assist as a 

 prehensile organ for taking in the biliary secretion on which the 

 animal feeds, whilst the pharyngeal sphincter will, as Simonds 



