PARASITOLOGY. 



157 



AcANTHOCEPHALA (Acanthos — thorn) 

 (Cephale — head) . 



This order belongs to the class Nemathelmintha 

 and includes a group of parasites that are round in 

 shape but are not provided with a digestive tract as 

 the order Nematoda ; they obtain nourishment by 

 absorption of digested nutrients from the intestinal 

 tract of the host; there are complete sexes, male 

 and female ; the cephalic (head) extemity is provided 

 with a globe-shaped proboscis armed with six rows of 

 booklets by which means it holds on to the mucous 

 membrane ; it includes the genus Echinorhynchus, 

 species of which infest the small intestines of the 

 dog, others infest birds and still another, the most im- 

 portant, infests the hog. 



( Echinos — spined) 

 Echinorhynchus Gigas (Rhynchus — proboscis) 

 (Gigas— giant). 

 Synonym. — Echinorhynchus hirudinaceous. 

 Distribution. — Very 

 common in the United 

 States ; also found in 

 Europe. 



Description .-Round 

 in shape, about two- 

 thirds the calibre of 

 a lead pencil, with 

 transverse markings. 

 Milk white in color; 

 the cephalic extrem- 

 i t y term in ate s 

 Fig. 61— EcHiNORHYNCHus GigAs, Female, abruptly and is pro- 



a, Globe-shaped proboscis, armed with six .j j .,-i ^i^u^ 

 rows of booklets. Vldcd With a globc- 



b, Caudal extremity. shaped proboSCis 



that is armed with six rows of booklets irregularly 



