350 



THE MITES 



man. In the course of five or six months the larvae (Fig. 1-iGC), 

 having migrated to the Hver or lymph glands, transform to the 

 second larval stage (Fig. 146E), reach a length of about one- 



FiG. 147. Head of a dog split in half to show three tongue-worms, Linguatula 

 rhinaria, (a) in the nasal cavity. Reduced in size. (After Colin, from Hall.) 



fourth of an inch, and consist of from 80 to 90 rings or segments, 

 each one with very fine denticulations on the hind margin. For 



a long time this larva was looked 

 upon as a distinct species. L. rhinaria 

 is nowhere abundant, even in its 

 normal hosts, though in some parts of 

 Europe about ten per cent of dogs are 

 said to be infected. The majority 

 of human cases reported have been 

 in Germany. 



Another species which is occasion- 

 ally found as a parasite in man dur- 

 ing its larval stage is Porocephalus 

 armillatus (Fig. 148). Unlike Lingua- 

 tula, this worm has a cylindrical body, 

 only about 18 to 22 rings of segments 

 and a total length of about one-half 

 an inch. The segments have no fine 

 denticulations as they have in Lingua- 

 tula. This species is said to spend its 

 adult life in the lungs of the African python, the larvae occurring 

 occasionally in man, but more frequently in giraffes, monkeys and 

 other African animals. Sambon thinks the eggs escape from the 



Fig. 148. Porocephalus armil- 

 latus; 9' female; $, male. 

 Natural size. (After .Sambon.) 



