BY W. J. RAINBOW. 343 



Plants. — 5. — Attractive colours. 



For the purposes of this paper it will suifice to divide the 

 Araneidce into two groups, namely: — 



1. — (a) Pi^otective colouration, and fh) formation. 



2. — Spiders that mimick : {^a janimate and (b) inanimate objects, 

 and (c) whose colours are attractive. 



Prot-ictive Colonraiion and Formation. — In the course of my 

 remarks, I have drawn attention to the fact that certain spiders 

 are protected by the uniformity of their colouration to suri-ound- 

 ing objects. Thus we have seen that while the colour of one 

 spider harmonises with that of the small and broken shells on our 

 sea-beaches, another group (Stephanopis) finds shelter by its close 

 resemblance to the bark of trees; then again, there are others 

 whose physical formation is protective, and of such are the genera 

 included in the subfamily of Gasteracanthuhf, whose hard, horny, 

 and generally spiny epidermis make them anything but tempting 

 morsels for insectivorous birds. 



Spiders ih'it miinick animate and inanimate objects, and ivhose 

 colours are attractive. — This grouj) contains those spiders whose 

 protection is secured, or who captui'e their prey by the mimicry 

 of animate and inanimate objects, and in this class we have the 

 extraordinary case of mimicry reported by Mr. Skuse, in which, 

 by the elevation of one pair of legs on each side of its body, 

 looping them together by the tarsi, and beating them rapidly up 

 and down, a certain species of spider, in addition to its coloura- 

 tion, adds that of the mimicry of a pair of wings, and thus 

 secures as pi'ey a certain dipterous insect. Again, there is the 

 no less wonderful mimicry by certain spiders, even to the most 

 minute detail, of birds' droppings — a form of mimicry that not 

 only secures them from the raids of their common enemies, but 

 also attracts those insects upon which they prey. 



Conclusion. — Taken collectively, these facts add an impoi'tant 

 link to the great chain of evidence upon which the law of natural 

 selection is based and Ijuilt. Much more might he added, but 

 sufficient has been given to illustrate the great truths comprised 

 in that law. I am indebted to my colleague, Mr. Edgar 

 R. Waite, for the admirable coloured drawing of Aciinopus 

 formosiis, which has been reproduced in Plate xx. 



