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 
hooklets 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 GiIGAs (Rhynchus—proboscis) 
(Gigas—giant). 
Synonym.—Echinorhynchus hirudinaceous. 
Distribution.—Very 
common inthe 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- 
: ity terminates 
Fig. 61—Ecninoruyncnvs Gigas, Femare. abruptly and is pro- 
fn boscis, d with six. : 
Bet Een re vided with a globe- 
b, Caudal extremity. shaped proboscis 
that is armed with six rows of hooklets irregularly 
