20 GUIDE TO INSECTS. 



calculated to render them inconspicuous, when waiting among leaves 

 either living or dry ; or on the bark of a tree as Acanthops does 

 (1137). Some species have bright colours beneath, and at a distance 

 this gives the appearance of a flower which may attract insects. 

 Idolum diabolicum (1143) from E. Africa is a good example of this. 

 The colours fade after death, but a plate from the Proceedings of 

 the Cambridge Philosophical Society is exhibited to show the natural 

 colours. 



The eggs of Mantidce are laid in a regular manner in flask- 

 shaped receptacles or egg-sacks, each sack containing several eggs. 

 The sacks are arranged one against the other, alternately right 

 and left, the whole series being enclosed in a capsule or envelope 

 (fig. 17a). These capsules have the appearance of being formed of 

 gelatinous matter. They are sometimes compact and hard, some- 

 times semitransparent and smooth. Usually the capsule has along 

 the upper side a ridge in which may be seen a number of small holes 

 or slits (fig. 17b). These are the openings of the sacks by which 

 the young escape ; they are not always visible. The transparent 

 capsules (1152) have the egg-sacks suspended by the sacks' necks. 

 The capsules are always attached to some object, such as a stone, 

 twig, or stem of grass. 



Family Blattid.^. 



Table- In Table-case 33 are examples of the Cockroaches, Blattidcz (1 1 70- 



case 33. 1193). One of the chief characteristics of this family is the great 

 development of the coxae, which occupy nearly the whole of the sternal 

 region. The legs are densely spined. The wings when present are 

 ample, the front pair are leathery and serve as covers for the hind 

 pair. The curve taken by the sixth vein, cutting off all the basal 

 part of the front wing, is a peculiarity only seen in this family. 

 Many species are without wings in both sexes. The female of the 

 common house Cockroach, or "black-beetle" (1177), has no wings, 

 and the female of Heterogamia cegyptiaca (1175) (where the 

 differences in the sexes are very great) and of many other species 

 are also wingless. The brown Ship-cockroach, Periplaneta americana 

 (1178), is winged in both sexes; in the female, however, they are 

 rather shorter than in the male. An interesting series of this species 

 (1193) is exhibited to show the curious attitudes of the insect when 

 cleaning itself. The antenna) are drawn down by means of the 

 front leg and then passed through the mouth to remove all dust. 

 One specimen has turned its head so as to clean the hind angles of 



