INSECTA. 327 



greater part of the superior portion of the abdomen. In various Hyme- 

 noptera, behind the scutellum and on the metathorax, we find a little 

 space called the post-sculellium. 



The ambulatory organs of locomotion consist of a coxa formed of two 

 pieces, a femur, an unarticulated tibia, and of a tarsus, which is 

 divided into several phalanges. The number of its articulations varies 

 from three to five, a difference which greatly depends upon the propor- 

 tional changes experienced by the first and penultimate joints. Although 

 their supputation may sometimes prove embarrassing, and this numeri- 

 cal series may not always be in exact accordance with the natural order, 

 it furnishes a good character for the distinction of genera. The last 

 joint is usually terminated by two hooks. The form of the tarsi is 

 subject to some modifications, according to the habits of the animal. 

 Those of aquatic species are usually strongly ciliated and flattened, 

 and resemble oars. 



The abdomen, which forms the third and last part of the body, is 

 confounded, in the Myriapoda, with the thorax : but in all other Insects, 

 or those which have but six feet, it is distinct. It contains the viscera, 

 &c., presenting nine or ten segments or annuli, some of which, however, 

 are frequently concealed or considerably reduced. The last annuli of 

 the abdomen, in several females, form a retractile or always projecting 

 ovipositor more or less complicated, which acts like an auger. A sting 

 is substituted for it in many of the female Hymenoptera. The female 

 lays her eggs, and deposits them in the way best adapted for their pre- 

 servation, and in such a manner that the moment the larvae make their 

 appearance, suitable aliment is always within their reach. Frequently 

 she collects provisions for them. This maternal solicitude often excites 

 our surprise, and more particularly unveils the instinct of Insects. In 

 the numerous societies of several of these animals, such as the Ant, 

 Termes, Wasp, Bee, &c., those individuals which form the greater por- 

 tion of the community, and by whose labour and vigilance the whole 

 community are maintained, have been considered as being of neither 

 sex. They have also been designated by the terms of labourers and 

 mules. It is now known, however, that they are females not fully 

 developed. 



The ova are sometimes hatched in the abdomen of the mother ; she is 

 then viviparous. The number of generations in a year depends on the 

 duration of each of them. Most commonly there is but one or two. 



A female Papilio, or Butterfly, lays her eggs, from which are hatched, 

 not Butterflies, but animals with an elongated body, divided into rings, 

 and a head furnished with jaws and several small eyes, having very 



