134 Captain C. E. Williams' Notes on 



probable that, as they have the power of producing such a 

 variety of colours, they may also possess that of assimilat- 

 ing their coloration to that of their environment. I hope 

 to be able to test this faculty on a future occasion. 



After the fifth month the nymphs remain a light or dark 

 brown, and appear to have lost the power of varying their 

 ground colour. The development of the black spot in the 

 centre of the prothoracic disc is a phenomenon of special 

 interest. As already stated, this is absent at birth. At 

 the first ecdysis, which takes place eighteen days after 

 hatching, it may be noticed that a portion of the pigment 

 around the posterior angle of the disc, on its ventral aspect, 

 becomes separated from the lateral portions, which later 

 disappear. The middle portion, really formed of two dots 

 one on each side of the middle line, is advanced centri- 

 petally at each succeeding moult, until at about the sixth 

 moult it reaches the centre of the disc. It retains 

 permanently its angular shape as an indication of its origin. 

 The attractive influence exercised by this intensely black 

 spot for the insects which form the prey of Gongylus is 

 enhanced by the total disappearance of all other black 

 pigment from the disc. An interesting comparison may 

 be made in this connection between Gongyhis and the 

 large African Mantis, Idoluin diabolicuiii, which is closely 

 related in form and habits to it. In the latter insect 

 the dark pigment at the posterior margin of the disc 

 is retained throughout life, but there is no central black 

 spot, and this species does not use its prothoracic expansion 

 for the purpose of floral simulation, but has it coloured to 

 resemble the foliage amidst which it conceals itself. 



The nymphs at the time of hatching measure from -^^ to \^ 

 inch in length, and increase by about one-quarter of their 

 length at each moult. The adult female measures four inches 

 from tip of cephalic crest to the posterior extremity of the 

 abdomen. The young nymphs feed mainly on mosquitoes ; 

 they will only take live victims on the wing, and will not 

 touch dead mosquitoes or those seated motionless in their 

 midst. At all stages the Mantis is fond of water, and in 

 captivity will die if this is not sprinkled over it frequently. 

 After the second moult house-flies are eaten, and a month 

 or so later bluebottle flies are captured. When walking 

 and climbing Gongylns uses the tarsi of its fore limbs as 

 well as of the two hinder pairs. If the tarsi of the fore 

 limbs are damaged it assists itself by the large tibial claw, 



