292 



MANUAL OF ZOOLOGY. 



known as "Beetles," and comprises an enormous number of 

 genera and species. They are remarkable, as a general rule, 

 for their hard polished integument, their glittering, often me- 



Fig. 120. a Rose-chafer (Cetoin'a aura to) and larva ; b Vine weevil 

 (Curculio sulcatus). 



tallic colour, and their voracious habits. They are grouped 

 by Latreille in the following four sections : 



1. Pentamera. Tarsus five-jointed. 



2. Heteromera. Tarsus of two anterior pairs of legs five- 

 jointed, of the posterior pair four-jointed. 



3. Tetramera. Tarsus four-jointed. 



4. Trimera. Tarsus three -jointed. 



DISTRIBUTION OF INSECTA IN TIME. The earliest known 

 insects have been discovered in the Devonian Rocks of 

 America, and consist of the remains of Neuroptera* Others, 

 as might have been anticipated, have been found in the Coal- 

 measures. In the Secondary Rocks remains of insects haye 

 been found abundantly in certain beds of the Oolitic and Liassic 

 formations. In some Tertiary strata Lepidoptera and other in- 

 sects have been found in a good state of preservation. Amber, 

 which is a fossil resin, has long been known to contain many 

 insects in its interior (in certain specimens) ; and all of these 

 appear to belong to extinct species, though amber, geologically 

 speaking, is not an ancient product. 



* The Devonian Ne-uroptera of North America are most closely allied to 

 the Ephemeridce; but one form is in many respects transitional between 

 the orders Orthoptera and Neuroptera, Insects belonging to the Neurop- 

 tera (viz., Miamia and Hemeristid), to the Orthoptera (Blattina), and to the 

 Hemiptera (Eugereon), have also been described from the Carboniferous 

 Rocks of North America. 



