(>00 



AKTICULATA. 



GARDEN-SPIDERS. 



VUtsH III. ARACHJVIBA. 



This class iucludcs spiders, scorpions, mites, <fec. ; they are distinguislicd by aerial respiration, 



and the possession of four pair 



of legs, attaclied to the anterior 

 part of the body. They have 

 no antenna} ; the jaws termi- 

 nate with a claw-like joint, 

 which conveys poison into the 

 wounds inflicted by them, this, 

 in the larger species only, being 

 injurious to man, though usu- 

 ally fatal to the insects on 

 which they prey. The legs are 

 generally formed of the same 

 joints as those of insects. All 

 the species are unisexual ; all 

 lay eggs, with the exception of 

 the scorpions and a few mites, 

 in which the ova are retained 

 in the oviduct till they are 

 hatched, and are thus pro- 

 duced alive. They are divided 



into five orders, the Dimerosomata, Polymer osomata^ Adelarthrosomata, Acarina or Monomeroso- 



mata, and Podosomata. 



ORDER 1. DIMEROSOMATA. 



This order derives its name from the Greek dimera, divided into two parts, and soma fa, bodies, 



and includes generally those creatures 

 which we call Spiders. In these the 

 body consists of two distinct portions, 

 of which the anterior, or cephalothorax, 

 is usually of an oval form, and covered 

 with a plate of a somewhat horny con- 

 sistence, while the posterior, or abdo- 

 men, fvenerallv forms a soft, roundish 

 mass, without any traces of segmenta- 

 tion, and which is attached to the base 

 of the cephalothorax by a narrow pe- 

 duncle. On its anterior portion the 

 cephalothorax bears six or eight sim- 

 ple eyes ; below and in front of these 

 are seen the large mandibles, which 

 serve these animals for the destruction 

 of their prey ; beneath is the opening 

 of the mouth, furnished with a pair 

 of masticating jaws, or maxillaj. These 

 organs occupy the front of the cephalo- 

 thorax ; the lower sui-face of this bears 

 four pairs of jointed legs, furnished at 

 their extremities with claws, which are often of a very singular, comb-like structure. 



THE GARDEN-SPIDER AND TRAP-DOOK SPIDER, 



