412 TEXT-BOOK OF ZOOLOGY 



flattened, thus enabling the animal to live among old papers and in 

 mouldering books, where it pursues book-lice (i.e., small Orthoptera) 

 and mites. 



ORDER V.: MITES (ACARINA). 



THE most familiar of these minute creatures are the beautiful scarlet- 

 red Scarlet Mites (TromUdium holosericeum] and the Water Mites 

 (Hydrachnidte). The former we often meet with on green plants, and 

 the latter, frequently in large numbers, in lakes, ponds, and pools. Both 

 display distinctly the characteristic features of mites viz., the thick-set, 

 unsegmented body, in which neither head, thorax, nor abdomen is 

 distinguishable. They live parasitically on the body- juices of other 

 animals either during their youth only or throughout the whole of their 

 existence. In fact, among the mites parasitism is general. 



The Beetle Mite (Gamasus coleoptratorum) lives as a bloodsucker on 

 the bodies of insects much employed on the ground. (Name such.) 



The Bird Mite (Dermanyssus avium) infests birdcages and poultry- 

 coops, and attacks the birds during the night. 



The Ticks (Ixodida) frequent dry woods. The females when they 

 have an opportunity bore into the skin of mammals, where they swell 

 up to the size of a bean. Even man is liable to be attacked by these 

 pests. By covering them with oil the creatures are forced to detach 

 their sucking proboscis, which, if force be used, remains in the wound 

 and causes inflammation. 



The Cheese Mite (Tyroglyphus siro} and its kindred live, often to 

 the number of millions, upon hard cheese and on dried fruits (plums), 

 where they form a white crust. 



To this order also belongs the Itch Mite (Sarcoptes scabiei), a small 

 microscopic parasite which bores its way under the skin of man, and 

 there forms long tunnels of hairy fineness. It there multiplies with 

 incredible rapidity, causing the disgusting disease known as the " itch." 



The " scab " or " mange " of dogs and other domestic animals is also 

 caused by mites. 



CLASS IV. : CRABS AND THEIR RELATIVES 

 (CRUSTACEA). 



ARTICULATE animals, breathing by gills (or merely by the skin) ; almost 

 exclusively aquatic ; usually possessing two pairs of antennae, and a pair 

 of appendages on every segment. 



