636 ZOOLOGY SECT. 



ORDER 8. HYMENOPTERA. 



Insects in which both pairs of wings are present and membran- 

 ous. The mouth parts are adapted both for biting and licking. 

 The prothorax is united with the other segments of the thorax. 

 There is a complete metamorphosis. 



Included in this order are Bees (Fig. 531) and Wasps, Ants 

 (Fig. 532), Gall-flies, and Ichneumons. 



Systematic Position of the Example. 



The Cockroach is a member of the order Orthoptera and of the 

 sub-order Orthoptera genuina, which comprises all the members of 

 the order with the exception of the aberrant group of the Earwigs 

 (sub-order Dermaptera). Of the Orthoptera geniiina there are 

 three divisions, the Cursoria, to which the Cockroaches belong; 

 the Gressoria, comprising the Manlidce and Phasmidce, or Stick- and 

 Leaf-insects and their allies ; and the Saltatoria, including the 

 Grasshoppers, Locusts, and Crickets. The division Cursoria com- 

 prises the single family of the Cockroaches (Blattidw), characterised 

 by the deflexed head, the flat oval body, the large prothoracic 

 tergum, the long antennae, the three pairs of legs similar, with 

 large coxae entirely covering the sternal surface of the thorax, the 

 five-jointed tarsi, and the presence of anal cerci. Pcriplaneta 

 belongs to a section of the family distinguished from the rest by 

 the femora being spiny underneath, and by the valvular character 

 of the last sternum in the female. 



3. GENERAL ORGANISATION. 



The exoskeleton of the Insecta (Fig. 515) consists of a chitinous 

 cuticle (cut.\ which varies in hardness and thickness in different 



Insects and in different parts of the 

 body of the same Insect, but is very rarely 

 ^ .;. ^_ calcified. Frequently it presents hexa- 



gonal markings ; sometimes it is perfor- 

 ated by numerous pores; sometimes it 

 is covered with thin scales; in many 

 cases it is developed into tactile hairs or 

 setm, which may be scattered over the 

 FIG. 5i5.-section through the body, or may be located only on certain 

 b^^tSeSSSJ; of ^ e appendages-the antennae, the 

 nit. layers of the cuticle ; maxillary and labial palpi, and the tarsi 

 (Afte? MiaiTand Denny.f*' of th e legs. In some, glands are present 

 in the integument odoriferous, honey- 

 secreting, or wax-forming glands; poison glands are present in 

 connection with an abdominal sting in certain Insects ; spinning 

 glands, forming a silky material, are confined to the larvae. 



