230 LINGUAT JLIDJE. MACROBIOTIDJE. 



years ; they are obtained by carefully squeezing out tlie contents 

 of pimples. The LINGUATULIDJB, or Tongue-worms, present far 

 less resemblance to the ordinary Acariua; they are elongated 

 worm-like, jointed creatures, which inhabit the lungs and frontal 

 sinuses of some Mammalia and the lungs of a few Reptiles. 



Their only exter- 



_^~~-!-r-rT r '^^TST^*^ na ^ or o ans consist 



*ux&3ZZu3^^ '^ of tw o P airs of 



very curious hooks 

 placed near the 



mouth. Until very lately these singular parasites were placed 

 amongst the Intestinal worms ; but recent researches into their 

 mode of development have shown that they are most nearly 

 allied to the Arachnida. The young, when just hatched, are 

 little, oval, mite-like creatures, furnished with four short, jointed 

 legs, and with the rudiments of a mouth at the anterior ex- 

 tremity. With age the body becomes greatly elongated and 

 distinctly divided into segments, whilst the vestiges of the four 

 limbs are to be found in the singular apparatus of hooks above 

 mentioned. The MACROBIOTID^;, or TARDIGRADA, forming the 

 third of these doubtful families of Acarina, include a number of 

 minute creatures, well known to microscopic observers as Sloth 

 or Bear- Anifhalcules. They are usually found in moss or in fresh 

 water, and have usually been placed with the Rotatorial Ani- 

 malcules. Their form is usually an elongated oval, and they are 

 furnished with four pairs of short legs, each of which usually 

 bears four little claws. The last pair is situated at the hinder 

 extremity of the body. The mouth forms a sort of rostrum. 

 Little or nothing is known of their habits ; and the most singular 

 circumstance connected with them is their power of returning to 

 life when moistened, after they have been for a considerable time 

 in a dry and apparently lifeless state. They may often be found 

 amongst the dust which collects in the gutters on the roofs of 

 houses. 



