INTRODUCTION. XIX 



of the Secondary period, and consist of three species (GJaj^i/njroiJtera 

 pterophylli, Curculionites j^^'odromns, and ChrysoinpJites Rothenhachi) : 

 the earliest recorded British species are from the Lias, and consist of a 

 good many species of Carahidre, Bapresfidce, Dijtisddce, Mdolon- 

 tlddce, &c. : throughout tlie Oohtic and Cretaceous rocks they are found 

 in greater or less numbers, and in the strata of the Tertiary period, as we 

 should expect, they become more and more common ; from two quarries 

 in the Upper Miocene near Lake Constance Heer took 2456 specimens 

 of Coleoptera, belonging to 518 species : we should naturally expect that 

 the Coleoptera would be preserved better than any other insects because; 

 of the hardness of their integument, and such in fact is the case : it 

 seems, therefore, all the more certain that they did not appear in the 

 Paheozoic periud. Those students who desire to examine into this very 

 interesting question are atlvised to consult the works of Mr. Scudder antl 

 M. Brogniart, and the valuable papers of Mi\ H. Goss in the " Proceed- 

 ings of the Geologist's Association," vols, v., vi., and ix. 



Internal Structure. 



The internal structure is discussed very fully in Burmeister's " Manual 

 of Entomology ;" it is not, however, necessary here to do more tlian 

 touch upon a few points. 



The organs of nidvitidn consist of the intestinal canal and its appen- 

 dages; this canal is terminated at one end by the mouth and at the 

 other by a vent or anus, which latter is invariably present in all perfect 

 insects, although in certain orders it is occasionally absent in the larval 

 state ; the hinder portions of the intestinal canal {duodenum, colon, 

 ccecum, &c.) need not here be discussed, but a few words may perhaps be 

 said upon its anterior appendages : the mouth opens upon a phar/pix, 

 which is the distended commencement of the cesophagus : the oesophagus 

 extends from the pharynx to the stomach, and in all orders (except the 

 Lcpidoptera, in Avhich it is forked) it passes through the entire cavity of 

 the thorax as a simple tube ; the third division of the intestinal canal is 

 the proventricidiis, a small narrow and tubular cavity, furnished within 

 Avith folds, teeth, spines, or projecting horny ridges ; it may, as Bur- 

 meister remarks, be considered as the mouth of the stomach, in front of 

 which it is directly situated : it is found in all mandibulate insects 

 Avhich feed upon hard substances or require their food to be triturated 

 previously to digestion : it is therefore present in all the carnivorous and 

 wood-feeding Coleoptera, l)Ut is not extended through the Avhole order, 

 and is not found in the suctorial orders of insects such as the Lcpid- 

 optera : it is more distinctly muscular than the rest of the intestinal 

 canal, and evidently answers to the gizzard of the gallinaceous birds. 



The stomach of the Coleoptera is rather variable in its formation : it 

 is of very simple structure, as might be expected from the nature of 

 their food, in the L-imcllicornia and Phytophaga, but in the Carnivorous 

 series it is much more coinph^x, being slu)rt and separated from the 



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