140 



KNOWLEDGE & SCIENTIFIC NEWS. 



[July, 1904. 



India — a species which has been known to naturalists for 

 upwards of three centuries, but of whose strange habits 

 nothing was discovered until comparatively recent years. 

 Living examples of Goiigylus have been thus described :" 

 " On looking at the insects from above they did not 

 exhibit any very striking features beyond the leaf-like 



Prothorax, Raptorial Limbs and Head of G. Onnniiloidrif in Fiower= 

 mimicking pose. The insect is hanging head downwards. 



expansions of the prothorax and the foliaceous append" 

 ages of the limbs, both of which, like the upper surface 

 of the insect, are coloured green, but on turning to the 

 under surface the aspect is entirely different. The leaf- 

 like expansion of the prothorax, instead of being green. 

 is a clear, pale lavender-violet, with a faint pink bloom 



G. <;on;(j i„i /«, as above. Raptorial Limbs expanded to seize prey. 



along the edges of the leaf, so that this portion of the 

 insect has the exact appearance of the corolla of a plant, 

 a floral simulation which is perfected by the presence of 

 a dark, blackish-brown dot in the centre, over the pro- 

 thorax, and which mimics the opening to the tube of a 

 corolla. A favourite position of the insect is to hang 

 head downwards among a mass of green foliage, and, 

 when it does so, it generally remains almost motionless, 



• Pro. Asiat. Soc. Bengal, 1S77, p. 193. 



but, at intervals, evinces a swaying movement as of a 

 flower touched by a gentle breeze ; and while in this 

 attitude, with its fore-limbs banded violet and black, and 

 drawn up in front of the centre of the corolla, the simula- 

 tion of a papilionaceous flower is complete. The object 

 of the bright colouring of the under surface of the pro- 

 thoracic expansion is evident, its purpose being to act as 

 a decoy to insects, which, mistaking it for a corolla, fly 

 directly into the expectant, sabre-like, raptorial arms of 

 the simulator." 



G, Gor.ni/: ^:'h\'. Key Diagram of Prothorax. Raptorial Limbs and 

 Head; and Ventral .Surface: Insect hanging head downwards. 



A more perfect combination of protective and alluring 

 resemblance than the above could hardly be conceived. 

 The green colouring of the body and legs of the Goiigylus 

 harmonises with the foliage amongst which it rests, and 

 affords an effective hiding from the sharp eyes of insecti- 

 vorous birds. The unusual shape and brightly-coloured 

 under side of its prothorax and fore-limbs constitute a 

 lure, by means of which the Mantis attracts to itself the 

 smaller insects upon which it feeds. 



Colour-PaLttern in Beetles. 



In \'o1. X. of the Decennial Publications of the Chicago 

 University, United States, \V. L. Tower gives the results of his 

 study of the development of colour and colour-pattern in 

 beetles and other insects. The colours of insects are of two 

 kinds. On the one hand, there is the dermal or typo-dermal 

 coloration, coeval with the group itself, and disposed in spots 

 and strips correlated with the underlying vital organs. On 

 the other hand, there is the coloration produced by scales or 

 modified hairs, which is of much later origin. The latter type 

 of colouring is solely ornamental, its development has had no 

 relation to the vital organs, and is, consequently, much more 

 diverse than the original colouring, which it tends to obscure. 

 .•\ good example of the difference between these two types of 

 colouring may be observed in the contrast between the dull 

 browns and yellows of the ground-beetles of the Catabus 

 genus, and the gay colouring of the Vanessa group of butter- 

 flies. Dermal colouring begins in the fore part of the body, 

 where the muscles first harden, and thence spreads to the 

 back. It is obviously concerned with the hardening of the 

 Cuticula, which has a tendency to turn brown, a fact which 

 accounts for the predominance of browns and yellows common 

 in beetles and cockroaches. 



