392 CHARACTERS OF INVERTEBRATE ANIMALS 



opening upon conical " spinnerets ", of which there are six in 

 the Garden-Spider, four large and two small. They will be found 

 as conical projections on the under side of the abdomen near its 



tip- 



The Garden- Spider possesses eight simple eyes, situated on 



the upper side of the cephalo-thorax, at its front end. Four of 



them are comparatively large and are placed at the corners of 



a square, on each side of which are a pair of rather smaller ones. 



As in Arachnids generally the young resemble the adult when 



hatched, except in size. 



There are two sub-orders: i. Segmented Spiders, and 2. 



Unsegmented Spiders. 



1. Segmented Spiders are represented by certain large East 

 Indian species, characterized by well-marked segmentation of 

 the abdomen and the possession of two pairs of lung-books, 

 agreeing in these respects with the whip-scorpions. A further 

 peculiarity is the presence of eight spinnerets, grouped together 

 on the under-side of the abdomen, and placed much farther for- 

 wards than in an ordinary spider. 



2. Unsegmented Spiders include all the common forms, of 

 which Epeira has been taken as a type. The sub-order is again 

 divided into two groups according to the number of lung-books 

 present, i.€. into Four-lunged Spiders and Two-lunged Spiders. 



Four - lunged Spiders include the largest members of the 

 order, which excavate burrows in the ground and line them with 

 silk, but do not construct snaring-webs. Some of these prey 

 upon small birds, e.g. the Bird-eating Spider {Mygale avicularid), 

 a gigantic South American form often seen in collections. Here 

 also are included the Trap-door Spiders (Cteniza and Nemesia) 

 of South Europe and elsewhere, which make hinged lids to their 

 burrows. There is only one British species {Atypus Sulzeri), 

 which burrows in damp earth. 



Two-lunged Spiders, of which Epeira diadema is a typical 

 example, embrace the large majority of species, and all the British 

 forms except Atypus. Only some of the kinds construct snaring- 

 webs, and among these may be mentioned, in addition to the 

 Garden-Spider, the common House-Spiders (Tegenaria domestica 

 and T. civilis), and the Hedge- Spider {Agalena labyrinthicd), 

 which constructs strong horizontal webs on bushes, hedges, &c. 

 A very interesting aquatic form is the Water- Spider {Argyroneta 



