224 



ZOOLOGY, 



nerally deposited on the skins of some other animal, froiil 

 these in a short time the larvse are hatched, which are desti« 

 tute of feet ; of a len^hened form, and thickly beset with 

 hair ; their larvse are often found in the nests of birds, attach- 

 ed to the young brood, on the juices of ^hich they feed; in 

 a few days they arrive at full growth, and then change into 

 the chrysalis state, the pupa is enveloped in a cotton like 

 case, these remain a longer or shorter time in this state, ac- 

 cording to the season of the year, in warm weather about 

 twelve days is the usual time ; when the perfect insect is 

 then developed. 



5. Acarus, Mite. "Palpi two jointed, shaped like thd 

 legs; eyes two, situated on each side of the head; legt 

 eight. 



The larger number of the Acari, are amongst the most 

 minute of the insect tribes, they feed on various substances, 

 but mostly on those in a state of decay ; some of the larger 

 kinds, as that well known insect the Tick, live on the juices 

 of other animals ; so numerous is this tribe, that perhaps it 

 is not too much, to say, that, almost every animal has 

 some one peculiar to the species. 



6. Hydrachna, Head, thorax^ and abdomen united ; feeU 



er^ two, jointed ; ea/e^ two, four, or six; legs eight, 

 ciliate, formed for swimming. 



An aquatic genus, feeding on the larvse of Tarious other 

 aquatic insects. 



I 



