PARASITES OF ANIMALS. 69 



NEMATODES. 



Heterakis compressa Schneider. Intestine of chicken. 



If. vesicularis Duj. Intestine of hens and turkeys. 



H. dispar Duj. Intestine of geese. 



Ascaris crassa Desl. Intestine of ducks. 



A. inflexa Rud. Intestine of hens. 



A.perspicillum Rud. Intestine of turkey. 



A. maculosa Rud. Intestine of pigeon. 



jSpirotera hamulosa. Gizzard of hens. 



S. uncinata Rud. Tubercles in oesophagus of geese. 



Syngamus trachealis Siebold. Windpipe, causing "gapes.'' 



Strongylus nodularis Rud. Gizzard and intestine of ducks 



and geese. 



In the preceding lists we have brought together most of the 

 parasites hitherto discovered in our more common domestic 

 animals. There can be no doubt but that many more will 

 hereafter be discovered. In the rabbit, Guinea-pig, parrots, 

 singing birds, and other animals often domesticated, many 

 additional species occur. 



In the following pages only the more common and impor- 

 tant species will be described. 



The Armed Tape-worm or Pork Tape-worm of Man (Tcenia 

 solium Linn.) ; and its young, the " measles" of pork and hu- 

 man flesh. 



This is perhaps the best known of all the numerous kinds of 

 tape-worms. Its young or larvae are common in the muscles 

 and other organs of hogs, and not very rare in man. (See 

 Figures 49-51.) In the adult stale it is, so far as known, pe- 

 culiar to the human intestine, where it is unnecessarily com- 

 mon! It grows to a great length, frequently ten to fifteen 

 feet, or even more, and is then composed of upwards of 800 

 joints, those that are sexually mature commencing at about the 

 450th segment. The head is small, about the size of a pin- 

 head, roundish, with four prominent suckers on the sides, and 

 a conical, proboscis-like top, around which there are two cir- 

 cles of sharp hooks, 22 to 28 in each circle (Figure 53). 

 The neck portion is slender, crossed by fine lines, which are 

 wider apart as they recede from the head, finally forming dis- 



