LINGUATULIDA ACARIXA. 



439 



testine and reach the liver. There they surround themselves with 

 a cyst, in which they pass through a series of changes of form, ac- 

 companied, as in insect larvae, by repeated ecdyses (fig. 378). When 

 six months have elapsed, they have attained a considerable size 

 and have acquired the four oral hooks, as well as a number of finely 

 serrated superficial rings. They have now reached the stage formerly 

 described as P. denticulatum (fig. 377), in which they break through 

 their capsules and begin a fresh migration. They traverse the liver, 

 and if present in great numbers, occasion the death of their host. 

 In other cases, on the other hand, they soon become enveloped in 



379. Ripe male of Aiax Sonzi, seen from the dorsal surface (after E. Claparede). Kt, 

 Pedipalpus; G, brain; Oc, eyes; T. testis ; Jf, Y-shaped gland; D, intestine; A, 

 anus ; Hd, cutaneous glands. 



another cyst. If they now pass with the flesh of the Hare or 

 Rabbit into the buccal cavity of the Dog, they penetrate into the 

 neighbouring air-chambers, and in two or three months become 

 sexually mature. 



Pentastomum tcenioides Rud., 80-85 mm., Male only 18-20 mm. long. P. 

 multlcinctum Harl., in the liver of Naja liaje. P. constrlctum v. Sieb. Encysted 

 in the liver of negroes in Egypt. 



Order 2. ACARINA,* MITES. 



Arachnida with stout body. The abdomen is unsegmented and 

 * 0. Fr. Muller, " Hydrachnse," etc., 1781. A. Duges, " Recherches sur 



