LINGUATULIDA OR PENTASTOMIDA. 



357 



water-beetles, and Atax on gills of fresh-water mussels. 

 Beetle-mites (Ga/iiastis}, often found on carrion beetles. 

 Ticks (Ixodes], on dogs, cattle, etc. 



...; - .* 



mm 



.v.. 



If 



J. 174. Follicle-niitc 

 (greatly enlarged). 



FIG. 175. Itch-mite (Sitrco/>lcs scabiei) 

 (greatly enlarged). 



Aberrant Orders or Classes. 



Order LINGUATULIDA or PENTASTOMIDA, e.g. 



t&nioides. 



Pentastomum 



This strange animal is parasitic in the nasal and frontal cavities 

 of the dog and wolf. It is worm - like in form, externally ringed, 

 without any oral appendages, but with two pairs of movable hooks near 

 the mouth. The muscles are striated. The alimentary canal is very 

 simple, without Malpighian tubes. A narrow circumcesophageal nerve - 

 ring, without a brain, is connected with a single ventral ganglion. 

 There are no sense organs nor trachere, nor is there any heart. The 

 sexes are separate ; the males smaller than the female. 



Embryos within egg-cases pass from the nostrils of the dog. If they 

 happen to be swallowed by a rabbit or a hare, or it may be some other 

 mammal, the embryos hatch in the gut and penetrate to liver or lung. 



