ACAEINA OR MITES. 



119 



minute embryo bores through the intestines and gets to the liver, 

 lungs, and mesenteric glands, where encystment takes place. 

 It here soon becomes converted into a simple roUed-up pupa (c), 

 with no legs, hooks, or bristles. By a repeated series of moults 

 a second larval form is reached (d), and which is said to last for 

 seven months, by which time it has grown to the length of one- 

 third of an inch. In this stage it was taken to be a distinct 

 species called L. denticulatum. Numerous spiny rows are 



Fia. 4S. — LlNUUATDLID^. 



A, Ovum. B, larva, c, pupal stage : a, anus ; &, mouth. D, Linguatula denticula- 

 tum. E, L. tseniodes. (Alter Eailliet and Leuokart.) 



present on the skin. They fall from the organs they were in, 

 to the body cavity and pleural spaces, and the majority die. 

 Some, however, encyst themselves in fresh parts of their host, 

 and even enter the air-tubes, and are so passed out of the host ; 

 or they may possibly enter the nasal cavities of the herbivora 

 they live in, during their early life. More generally they reach 

 maturity in the nasal cavities of the carnivora which happen to 

 eat the flesh of infected herbivorous animals. In this last host 



