APT 



APU 



siderable flocks. They are found in the 

 same places as the papuan penguins, and 

 not unfrequently mixed with them; but in 

 general show a disposition of associating 

 with their own species. See Plate III. 

 Aves. fig. 6. 



AFTER A, in the Linnaean system of 

 zoology, the seventh and last order of in- 

 sects, the distinguishing characteristic of 

 which is, that the insects comprehended 

 in it have no wings. Of this order there 

 are three divisions. In A. the insects are 

 distinguished by having six legs ; head 

 distinct from the thorax : there are five 

 genera ; viz. the 



Lepisma, 



Pediculus, 



Podura, 



Pulex, 

 Termes. 



In the division B, the insects have from 

 8 to 14 legs ; head and thorax united : of 

 these there are eight genera ; viz. the 



Acarus, 

 Aranea, 

 Cancer, 

 Hydrancha, 



Monoculus, 

 Oniscus, 

 Phalangium, 

 Scorpio. 



In the division C, the legs are nume- 

 rous ; head distinct from the thorax ; of 

 which there are two species ; viz. the 



Julus, and 

 Scolopendra. 



This order comprehends all kinds of 

 spiders, the lice of different animals, scor- 

 pions, and crabs. Upon these we may 

 make a few general observations. The 

 nets spread out by spiders, to catch their 

 prey, are composed of similar materials to 

 the silk of the silk-worm, and are also 

 spun from the animal's body. The cob- 

 webs of the gossamer are frequently seen 

 floating in the air in a sunny day, and are 

 sometimes so abundant as to fall in show- 

 ers. Each of these has been compared to 

 a balloon transporting the little aeronaut 

 that formed it, by means of its specific 

 lightness. This species of spider attach- 

 ing its first formed thread to the leaf or 

 branch of a tree, by dropping to a certain 

 distance lengthens it, then climbs up the 

 thread, and dropping again, draws out 

 another, and so on, till a sufficient quan- 

 tity of this silk is formed to buoy ihe spi- 

 der up in the air. He then separates the 

 \\hoit- from the leaf, and running down to 

 his seat at the bottom, trusts himself and 

 his balluon to the Mercy of the wind. Ma- 

 ny species of spiders effect the same thing 



by attaching themselves to an eminence 

 by their claws, and after ejecting a suffi- 

 cient quantity of web, which is wafted on- 

 wards by the wind, they suddenly relax 

 the hold, and appear to spring into the 

 air. By this method these animals are 

 transported from tree to tree, and from 

 wood to wood, in search of food. The 

 cobwebs that are spread over the surface 

 of the grass, and that offer so beautiful an 

 object to the eye early in the summer's 

 morning, through the brilliancy of the 

 dew-drops formed and suspended on their 

 silken threads, and the reflexion of the 

 sun's rays from each, are the work of 

 another species of spiders. 



The different kinds of lice are exceed- 

 ingly numerous, almost every kind of ani- 

 mal having its particular sort of vermin. 

 They are all carnivorous, or perhaps ra- 

 ther sanguivorous insects, living on the 

 blood of other animals. Their eggs are 

 all nits. The Scorpio genus abound in 

 hot climates, and are troublesome in ne- 

 glected places, and where cleanliness is 

 not attended to. The crab tribes cast their 

 shells every year, and are then in a soft, 

 helpless state, unable to make resistance, 

 and therefore at that time become the 

 prey of many kinds offish, when not pro- 

 vided with a guardian. It is a remarkable 

 fact, that the edible crab of the United 

 States, when in this state of imbecility, 

 places itself, for security, under the pro- 

 tection of one of its own species whose 

 shell is hard and firm. This confidence is 

 never misplaced ; his protector defends 

 him against every assault at the risk of 

 his own life or limbs and even when 

 taken in the net, and thrown on shore, is 

 still firmly held by his faithful companion. 

 Their shells, but more especially those of 

 the class testacea, afford a principal con- 

 stituent in the formation of chalk-beds, 

 and beds of marl, which are formed at the 

 bottom of the sea. Specimens of entire 

 shells are frequently met with in chalk- 

 pits which are now many miles inland ; 

 and there is little doubt that, in a commi- 

 nuted state, they form a principal ingredi- 

 ent in most calcareous earth. Under each 

 genus will be found an account of a few 

 of the more remarkable species. See 

 ACARUS, ARANEA, CANCER, SCORPIO, &c. 



APUS, in astronomy, a constellation of 

 the southern hemisphere, placed near the 

 pole, between the Triangulum Australe 

 and the Chameleon, supposed to repre- 

 sent the bird oi paradise. There are four 

 stars of the sixth, three of the fifth, and 

 four of the fourth magnitude, in the con- 

 stellation Apus. Dr. Haley, in 1677, ob- 



