THE SPIDERS OF EPPING FOREST. igi 



find perfect gradations from the most ancient stock to the most 

 highly specialised species. The early attempts at a systematic 

 classification, not only of the Araneae hut of almost all the 

 Natural Orders of animals, were more or less of the nature of an 

 arrangement, founded upon the most evident structural differences, 

 intended to facilitate the conversion of a visibly heterogeneous 

 order into several groups possessed of something like homo- 

 geneity. With the general acceptance of the various theories of 

 evolutionary science, the systematist has not only endeavoured to 

 elucidate the relation existing between order and order, or family 

 and family, but has essayed to trace the development, through 

 successive stages, of the most highly specialised creatures from 

 the primary representatives of the group under his consideration. 

 The order Araneae is, broadly speaking an exceedingly homo- 

 geneous one and the difficulty of satisfactorily characterising the 

 various groups is exaggerated by the simplicity of structure 

 exhibited. It should be borne in mind that the development of a 

 group of animals from an original stock cannot be truly repre- 

 sented by any linear arrangement but rather by a genealogical 

 '' tree," the "root" corresponding to the elementary, and the 

 " twigs " to the most highly specialised forms. In dealing with 

 the evolutionary development of the Araneae I am aware that I 

 am venturing upon dangerous ground. In this matter modern 

 araneologists are not by any means agreed, as a very cursory 

 glance at the more recent English and Continental publications 

 will show ; and I trust, therefore, that the accompanying diagram 

 (Plate IX.) may be regarded simply as expressing the opinion of 

 a single individual. 



ORDER ARANEAE. 



Head and thorax fused to form a single piece. Eyes simple. Abdomen 

 almost invariably non-segmented, connected with the thorax by a slender 

 pedicle, terminated by several pairs of spinners, each furnished with numerous 

 spinning tubes. Respiratory organs consisting of laminal tracheae and tube 

 tracheae, both kinds being usually found in one individual. (The tube tracheae 

 are occasionally absent ; and, very rarely, the laminal tracheae are wanting). 

 Reproductive organs of both sexes situated between the anterior spiracular 

 openings, but the ejactorial apparatus of the male is connected with the 

 terminal joint of the palpus. Falces consisting of a stout basal joint and a 

 movable fang, pierced with a channel and capable of injecting a poisonous 

 fluid. Sternal plates two in number. Palpus of the female pediform. Legs 

 eight, each consisting normally of seven joints. 



