^^ 324, 325. THE INSECTA. 403 



like, and colored. Their forms vary infinitely not only according to the 

 species, but also according to the regions of the body. They are often ribbed 

 longitudinally, and denticulated or deeply serrated on their borders. These 

 scales are often inserted on the skin perpendicularly, thus forming a pelt- 

 like covering easily wiped off; sometimes they are imbricated and exactly 

 fitted to each other. '^' 



§ 324. 



The various parts of the cutaneous skeleton of the Insecta have been so 

 carefully studied in Zoology, that they may well be passed over here. As 

 the internal surface of this skeleton furnishes points of insertion to the vol- 

 untary muscles, the segments of the body on which these last are attached, 

 would naturally be developed in proportion to their volume. Thus with those 

 Insecta which have powerful masticatory organs, the head is remarkably large 

 on account of the prominent development of the masticatory muscles ; in 

 the same way likewise other fossorial, rapacious, or saltatory Insecta, indicate 

 their habits of life by the size of their legs, which are endowed with great 

 muscular power. It is for the same reason, also, that with the species 

 which fly, the mesothorax and metathorax are so largely developed ; for 

 these contain not only the muscles of the last two pairs of legs, but also 

 those of the wings. These relations are especially distinct in those families 

 or genera which embrace both winged and unwinged species. 



On the internal surface of the cutaneous skeleton, are found, in the head 

 and thorax, processes which may be regarded as an internal skeleton 

 Some of these serve as septa, which separate certain organs, and others 

 furnish points of insertion to muscles, and then are often bifurcated.^" 



CHAPTER II. 



MUSCULAR SYSTEM AND LOCOMOTIVE AND SONIFEBOUS ORGANS. 



§ 325. 



The muscular fibres of the Insecta are striated, not only in the voluntary 

 muscles, but often also in those of organic life, as in the stomach and intes- 

 tine.''' All are colorless or of a dirty yellow color. This last is especially 

 observed with the muscles of the thorax belonging to the wings, which differ, 



3 This covering has a velvety aspect with the Dujardin, Observ. au microscop. p. 121, PI. Vn. 



Lepidoptera, Anthracidae, and Bombylidae ; it is IX. XI. XII. ; Nicolet, loc. cit. p. 22, Pi. II. 



scaly on the bodies of many of the Curculionidae, (Poduridae), and H. Fischer, Isis, 1846, p. 401, 



Melolonthidae, Clavicornes, Lepismidae, Poduridae Taf. IV. (Coleoptera). 



and on the wings of the Culicidae, and Lepidoptera. 1 For the internal skeleton of the Insecta, see 



It has always excited the attention of naturalists, Audouin, Ann. gener. d. Sc. physiq. VII. p. 182, 



who have figured it in their works. See also or MeckePs deutsch. Archiv VII. p. 435 ; 



Reaumur, and Degeer, loc. cit., also Lyonet, Eschscholtz, Isis, 1822, p. 52 ; Burmeister, 



M^m. du Museum, XX. p. 82, PI. VI.-XI. ; Ber- Handb. &c. I. p. 251, and Newport, Cyclopaed. 



nard-Deschamps, Ami. d. Sc. Nat. III. 1835, PI. loc. cit. II. p. 909. 



UI. IV. j Ratzeburg, Die Forstinsekt. II. Taf. I.; 1 Nicrophorus. 



