84 Mr. R. I. Pocock on the Genus Poecilotheria. 



In addition to their great size, a feature in which they are 

 scarcely surpassed by any spider in any country, the species 

 of Foecilotheria are remarkable for their varied colouring. 

 The upperside of the body and limbs is ornamented with 

 blotches and stripes of brown and grey ; and since it is now 

 known that the spiders live on trees, there can be no doubt 

 that this type of coloration subserves the purpose of conceal- 

 ment, since it must harmonize very closely with the pattern 

 of a tree-trunk overgrown with patches of grey lichen and 

 moss. But the colouring of the lower side is startlingly 

 different from that of the upper, and is quite unlike anything 

 that is to be met with in the spiders allied to Fcrcilotheria, 

 though coloration of a similar kind is known to occur in many 

 species of the families Lycosidte, Heteropodida^, &c. This 

 coloration in most species consists of a deep chocolate-brown 

 or black tint on the lower side of the thorax, abdomen, and 

 coxa?^ while the legs are nearly white or lemon-yellow, 

 beautifully slashed with black bands and tipped with hairy 

 pads of iridescent hue. It is at first sight puzzling to account 

 for the existence of such colours on the lower surface of a 

 spider, where under ordinary circumstances they cannot 

 possibly be seen. But it is known that when molested these 

 animals rear themselves on their hind legs and brandish the 

 fore pairs and palpi in the air, adopting, in fact, a position 

 in which the colours are plainly displayed to vieu-. Some of 

 the other spiders mentioned above belonging, e. g., to tiie 

 Heteiopodidge, which, although small as compared with 

 Poecilotheria^ are yet of considerable dimensions, are known 

 actually to turn on their backs when molested. Taking 

 these facts into consideration, and remembering that black 

 and white or black and yellow stripes constitute the badge 

 with which Nature, for purposes of protection, has endowed 

 poisonous or inedible animals, so (hat they n)ay be at once 

 recognized by their foes and let alone — remembering, too, 

 that these spiders possess poison-glands of large size and 

 are armed with irritating bristles, I have no hesitation in 

 ascribing the unusual coloration of the under surface to the 

 category of warning characters. They also possess a method 

 of self-advertisement, which no doubt subserves the same 

 end, in the form of a stridulating-organ lodged between the 

 mandible and tiie palp, and consisting of vibratile club-shaped 

 rods and of bristles which set them a -sounding. 



During 1898 the British j\Iuseum received from Mr. 11. R. P. 



Carter '^ representatives of three new species of Poecilotheria ; 



• I gladly tiilve this opportunity of expiessing my great obligation to 



