34 MODERN CLASSIFICATION OF INSECTS. 



in the last edition of this work, the last-named insect was still retained, 

 from the straight suture by which the upper wings are united when 

 unemployed. These insects, however, although nearly agreeing with 

 the beetles in the structure of the mouth, are widely separated by 

 the nature of their metamorphoses, which consist in a simple cast- 

 ing of the skin from time to time, the larva nearly resembling the 

 perfect insect, the pupa being also similar, but furnished with rudi- 

 mental wings, and being active ; whereas, in the beetles, the larva is 

 quite unlike the beetle, and the pu[)a inactive. So that, on the whole, 

 this may be considered as one of the most definitely marked grouj:)s 

 of the animal kingdom. Mr. MacLeay has indeed (^Horce EntomoL 

 p. 421.) considered its insulation as the result of accident, although it 

 is a group of that precise kind which he has since proved (in his 

 Letter upon the Dichotomoiis Sz/stem) to be a perfectly natural one. 



The number of species of this order with which entomologists are 

 actually acquainted cannot be less than 35,000* ; and it is more 

 than probable that, when the number of species of foreign climes shall 

 have been collected, the number will be doubled, if not trebled, as we 

 may, indeed, conceive by noticing the great proportion of European 

 species already in the lists. In this surprising number we find the 

 most brilliant colours and most singular forms, with a variation of 

 size from the most bulky to the most minute of the insect tribes. 

 Hence, it is not surprising that these insects should have attracted 

 the great, and even absolute, attention of so many authors and ama- 

 teurs ; and which has probably been increased by the comparative 

 largeness of size and superior consistence of their external covering, 

 whereby they are rendered so much easier in collection, preservation, 

 and examination. 



In addition to the characters given above the following may be men- 

 tioned : — The head is furnished with a pair of antennae, of which the 

 form varies very greatly, even in the sexes of the same species, but 

 which, except in a few instances, consist of eleven joints. The eyes 

 are large and lateral ; and, in a few species, each is divided by a horny 

 sinus (being part of the skull), so that in these four eyes appear to 

 exist, an example of which occurs in Gyrinus. The simple ocelli 

 are here wanting, except in Paussus bucephalus, and some of the 

 small Staphylinidse, in which Dalmann observed two tubercles on the 

 crown of the head, which he considered to be ocelli, but Latreille 



* The Berlin Museum alone contains 28,000 species. 



