1884.] NEW GENERA OF SPIDERS. 199 



Ornithoscatoides decipiens. (Plate XV. fig. 1.) 



Thomisus decipiens, Forbes, P. Z. S. 1883, p. 586. 



Adult female, length rather above C>1 lines. 



The general colour of this Spider is a lioary or yellowish ashy 

 grey marked with black. The abdomen has a large, somewhat 

 quadrate black patch at the middle of its hinder extremity ; on this 

 patch are placed eight shining roundish dark-brown tubercles ; the 

 four largest form a transverse, unequally sided parallelogram at the 

 fore part of the black patch ; the other four, which are much the 

 smallest, form a longer transverse parallelogram immediately behind 

 the other. At the hinder part also, on either side of the shining 

 tubercles, are several strong tuberculiform eminences or promi- 

 nences, of a similar kind to which are also four small ones in a 

 transverse line at the extreme fore margin ; some other depressed 

 spots or pits are also disposed on the upper surface, with a dark 

 blackish suffused patch at the middle of the anterior extremity, and 

 another on each side just iu front of the foremost lateral eminence. 



The cepludothorax has a black irregular patch on each side of the 

 hinder part of the thoracic region. The ocular region is somewhat 

 suffused with blackish, and an irregular black, somewhat V-shaped 

 marking indicates the junction of the caput and thorax. The two 

 anterior pairs of legs have some black suffused markings on the 

 upper side of the femora, the fore half (or rather more) of the tibiae, 

 metatarsi, and tarsi of those two pairs being almost wholly black ; 

 while the two hinder pairs have only an irregular black marking 

 here and there. The spines on the tibiae and metatarsi of the first 

 and second pairs of legs are numerous, long, strong, and con- 

 spicuous. 



The pale spines (mentioned above) on the upper sides of the 

 femora are used, according to Mr. Forbes's observations, to secure the 

 Spider on its back to a patch of whitish silk spun upon the surface 

 of a leaf. When so secured the Spider has the exact appearance of 

 the droppings of some hird, and the white silk patch emerging 

 irregularly outside the Spider has the appearance of the more 

 liquid portion of the droppings flowing out and drying on the leaf 1 . 

 The eyes of each row respectively are equidistant from each 

 other, but those of the fore- central pair form a shorter line than 

 those of the hind-central pair. The four central eyes form a square 

 whose anterior side is the shortest ; and the height of the clypeus, 

 which projects forwards, is nearly about equal to half that of the 

 facial space. 



1 Mr. Forbes lias, since the above was printed, remarked to me that in tho 

 two instances which came under his notice, the resemblance extended even to 

 the running down of the fluid excreta towards the lower side of the sloping leal', 

 ending in a kind of knob. Mr. Forbes also expressly disclaims the idea of 

 crediting the .Spider with any conscious design, but he says" that the similitude 

 is so exact that the Spider might have had consciousness— i. e. it could not have 

 been more exact if the Spider did have it." Is not its exactness probably the 

 result of the unconsciousness of the Spider? Conscious design would possibly 

 have resulted in failure and abandoning the plan, or at best in a more clumsy 

 imitation. 



