THE ORDERS OF THE HEXAPODA. 49 



CCC. Mouth-parts formed for sucking; viz., with the mandibles and max- 

 illae bristle-like. V. Hlmiptera. 



BB. Insects with a complete metamorphosis. {Metadata.) 



C. Mouth-parts formed for biting; viz., both mandibles and maxillae in the 

 form of jaws. 



D. The two pairs of wings similar in structure, membranous, with many 

 veins and cells. VI. NEUROPTERA. 



DD. The first pair of wings much thickened (horny) throughout their 

 entire length, and meeting in a straight line down the back ; the sec- 

 ond pair membranous. IX. COLEOPTERA. 

 CC. Mouth-parts formed for both biting and sucking; viz., with the man- 

 dibles in the form of jaws ; and with the maxillae and labium fitted for 

 taking liquid food. Both pairs of wings membranous, with few veins 

 and cells. X. Hymenoptera. 

 CCC. Mouth-parts formed for sucking. 



D. With four wings clothed with minute imbricated scales ; mandibles 

 rudimentary; maxillae developed into a sucking tube. 



VII. Lepidoptera. 

 DD. With only two wings ; the hind wings represented by a pair of 

 knobbed, thread-like organs ; mandibles and maxillae bristle-like. 



VIII. DlPTERA. 



TABLE FOR DETERMINING THE ORDERS OF HEXAPODA. 



(This table includes only adult insects.) 



A. Wingless or with rudimentary wings. 



B. Mandibles and maxillae retracted within the cavity of the head so that 

 only their apices are visible. I. THYSANURA. 



BB. Mandibles and maxillae more or less prominent and fitted for biting. 

 C. Head with long, trunk-like beak. (Boreus.) VI. Neuroptera. 



CC. Head not prolonged into a trunk. 



D. Louse-like insects of small size; body less than one-sixth inch in 

 length. {Book-lice and Bird-lice.) II. Pseudoneuroptera. 



DD. Insects of various forms, but not louse-like, and, except in the case 

 of some ants, with the body more than one-sixth inch in length. 

 E. Abdomen with short, conical, compressed, many-jointed caudal 

 appendages. {Cockroaches.) III. Orthoptera. 



EE. Abdomen without jointed caudal appendages. 



F. Legs fitted for jumping. {Wingless Locusts, Grasshoppers, and 

 Crickets?) III. ORTHOPTERA. 



FF. Legs fitted for running. 



G. Abdomen broadly joined to thorax. 



H. Body linear. {Walking-slicks.) III. Orthoptera. 



HH. Body white and somewhat ant-like in form. ( Tcrmes.) 



II. Pseudoneuroptera. 



HHH. Body neither linear nor ant-like in form. ( Wingless 



Fire-ply et a I.) IX. COLEOPTERA. 



