COLEOPTERA. 495 



The homology of the elytra is most easily understood by 

 a study of the corresponding parts in other orders of in- 

 sects. In the lower orders of insects there exists at the 

 base of each wing a small sclerite ; these have been termed 

 the paraptera (pa-rap'te-ra), from the Greek para, beside, 

 and pteron, a wing. In some of the orders of insects the 

 paraptera of the mesothorax are in the form of a cup-like 

 scale over the base of each fore wing, and are termed the 

 tegul(B\ this form is well shown by most Hymenoptera. In 

 the Lepidoptera they are even more prominent, and in many 

 cases extend back a considerable distance on each side ; 

 those of this order have been named the patagia. In the 

 Coleoptera the paraptera of the mesothorax reach their 

 greatest development, and so strongly resemble wings that 

 they are still commonly believed to be the fore wings. 



The hind wings are membranous, and in most species very 

 efficient organs of flight. But in some of the pre-eminently 

 running beetles the hind wings are wanting, and the elytra 

 serve only as a protection to the abdomen. With some of 

 these insects the elytra are even grown together where they 

 meet on the middle line of the back. Instances of this kind 

 are not uncommon among the ground-beetles and the dark- 

 ling beetles. 



The different mouth-parts are very evenly developed ; 

 we do not find some of them greatly enlarged at the ex- 

 pense of others, as in several other orders of insects. The 

 upper lip, or labrum, is usually distinct ; the mandibles are 

 powerful jaws fitted either for seizing prey or for gnawing; 

 the maxillae are also well developed and are quite compli- 

 cated, consisting of several distinct pieces; the maxillary 

 palpi are usually prominent ; and the lower lip, or labium, is 

 also well developed and complicated, consisting of several 

 parts and bearing prominent labial palpi. 



The larvae are commonly called grubs. They are usually 

 furnished with six thoracic legs, and often with a single 

 proleg at the caudal end of the body ; some, however, as 



