THE PEXTASTOMIDA. 



335 



The Pentastomida are elongated vermifjorm animals, the 

 bodies of which are divided by close-set transverse constric- 



Fie. y^.—Pentastomum tcenioides.—K. Male. B, Female. C. Anterior end of the body : 

 «, anterior hooks ; 6, posterior hooks ; d, mouth ; c, rudimentary palpiform or- 

 gans. (After Leuckart.) 



tions into numerous short segments. At first sight they 

 appear to be entirely devoid of appendages, but, on careful 

 inspection, four curved hooks are found, two on each side of 

 the mouth, which is situated rather behind the anterior ex- 

 tremity of the body. Each hook is solid, and its base pro- 



Fig. 94.— Embryo of Pentastomum tmnioides. 



jects into the cavity of the body and gives attachment to the 

 muscular bands by which it is moved. 



The mouth is surrounded by a chitinous ring ; a narrow 

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