38 INVERTEBRATE ZOOLOGY. 



tion originally for aquatic breathing and 

 still retained in a few aqnatic larval 

 forms. The higher insects have gained 

 secondary larval forms and thus develop 

 by a metamorphosis. 



Order 1. Thysaneura Minute wingless forms, with biting 



month parts, found in decayed wood 

 and damp earth. They are the most 

 primitive insects and have never devel- 

 oped wings. Some show rudiments of 

 of abdominal legs. Ametabolic, i. e. de- 

 velopment direct. -^ Podura. 



Order 3. Pseudoneuroptera Mouth parts biting, wings all alike, trans- 

 parent, delicate, with lace-like venation. 

 This group was formerly united with the 

 Neuroptera, but has an active pupa 

 (hemimetabolism ) . 

 if Libellula, Ephemera. 



Order 3. Orthoptera Mouth parts biting — upper wings parch- 

 ment-like, generally narrow — under 

 wings membraneous and often folded. 

 Development hemimetabolic i. e. pupa 

 active. -^ Caloptenus. 



Order 4. Neuroptera Mouth parts biting— somewhat modified 



in Phrygnnidae. Wings as in Order 2. 

 Development holometabolic i. e. pupa — 

 quiescent. -^ Phryganea. 



Order 5. Coleoptera Mouth parts biting — upper wings (elytra) 



forming hard shields for the protection 

 of the membraneous lower ones. Holo- 

 metabolic. Thorax free and quite dis- 

 tinct from the posterior portion, thus 

 dividing the body into three regions,, 

 head, pro-thorax, and meso- and meta- 

 thorax + abdomen. Holometabolic. 

 if Carabiis. 



