180 



INTRODUCTION TO ZOOLOGY 



CHAP. 



spoken of as the mandibles, though probably not homologous 

 with the mandibles of insects), and a pair of six- jointed feelers, 

 very like legs, known here as the pedipalps. The last joint of 

 the latter contains, in the adult male spider, a complex " palpal 

 organ " a sexual organ in which the sperm cells are tem- 

 porarily stored (Fig. 114, pp). The structure and life- 

 history of the Common Garden Spider will elucidate many 

 points in the structure arid life -history of the Araneae 

 generally. 



General 

 Form. 



Type : The Common Cross Spider (Epeira diademata). 



Epeira diademata is the largest of our common garden 

 spiders, and in the autumn, when it is full grown, it is easily 

 found in nearly every garden, where its large, vertical, beauti- 

 fully constructed web will be 

 hung in many a sheltered corner. 

 The spider is a 

 brownish-yellow or 

 reddish-brown 

 colour of varying shades, and it 

 can readily be recognised, when 

 viewed from above (Fig. 113), 

 by the white spots and lines 

 on the back of the abdomen, 

 arranged in the form of a cross, 

 whence the creature gets its 

 name of " cross " spider. The 

 body of the female spider may 

 be quite f ths of an inch long, 

 but the male is a little smaller. 

 In a dorsal view, the union of 

 head and thorax is obvious, but 

 the constriction between thorax 

 and abdomen is largely hidden 

 by the overhanging of the 

 latter. 



On the head of the spider shown, can be seen 

 the eight simple eyes and the forwardly projecting 

 pedipalps, but the jaws, which hang down vertically, are not 

 visible. These are best examined from a front view such as 



FIG. 113. The Common Cross Spider 

 (Epeira diademata). 



(View from above. The line to the right 

 shows the actual length.) 



The Head. 



