234 ORTHOPTERA 



on the two tegmina, as shown in Fig. 128, A, but are so arranged 

 that when the tegmina are closed (Fig. 128, B) a symmetrical 

 pattern is produced by the combination of the marks of the two 

 differently spotted tegmina. It is very curious to notice the 

 great difference in the colour of the part of the right tegmen 

 that is overlapped by the edge of the left one ; this part of the 

 tegmen being colomred orange yellow in harmony with the wings. 

 The result of the remarkable differentiation of the coloiu'S of the 

 two tegmina may be summarised by saying that on the right 

 one the colour of a part is abruptly contrasted with that of the 

 rest of the organ, so as to share the system of coloration of the 

 under-wings and body, while the corresponding part of the other 

 tegmen is very different, and completes the system of symmetrical 

 ornamentation of the upper surface. 



Many other members of the Blattidae have an elegant 



appearance, and depart more or less from their fellows in 



structural characters, with the result of adding to their graceful 



appearance ; in such cases, so far as at present 



known, these Insects are brightly coloured. 



Thus Hypnorna amoena (Fig. 129) has the 



antennae banded in white, black, and red, 



while the overlapping part of the tegmina is 



arranged so as to bring the line of junction 



between them nearly straight along the middle 



line of the body, and thus produce a more 



symmetrical appearance than we find in other 



Fig. 129. — Hypnorna cockroaches. The head in this Insect is not 



Americr.' Tri^Oxy- ^° Concealed as usual, and this undoubtedly 



haioides. (After de adds somewhat to the effective appearance of 



aussure.) ^j^-^ cockroach. This visibility of the front of 



the head in Hypnorna is not, as would be supposed, owing to 



its being less inflexed than usual. On the contrary, the head is 



quite as strongly inflexed as it is in other Blattidae, but the 



part just at the front of the thorax is unusually elongate, so 



that the eyes are exposed and the Insect has a larger field of 



vision. This interesting Insect belongs to the tribe Oxyhaloides 



[Plectopterinae Sauss.J, in which group the most highly developed 



folded wings occur. 



The wingless forms never exhibit the grace and elegance 

 possessed by some of the more active of the winged Blattidae. 



