338 INSECTA. 



joints. Although their supputation may sometimes prove embarrass- 

 ing, and this nvmierical series may not always be in exact accordance 

 with the natural order, it furnishes a good character for the distinc- 

 tion 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 j^art 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 and the sexual organs, presenting nine or ten segments or 

 annuli, some of Avhich, however, are frequently concealed or con- 

 siderably reduced. The organs of generation are situated at the 

 posterior extremity and issue through the anus. The luli and 

 Libellulse alone constitute exceptions. The last annuli of the abdo- 

 men, in several females, form a retractile or always projecting 

 ovipositor — oviscapte of Marcel de Serres — more or less complicated, 

 which act as an auger. A sting is substituted for it in many of the 

 female Hymenoptera. The fecundating organ of the male is almost 

 provided with hooks or a forceps f . The sexes usually copulate but 

 once, and this junction in certain genera is even suflRcient for the 

 fecundation of several successive generations. The male places 

 himself on the back of his mate, and remains there for some time. 

 The latter soon lays her eggs J, and deposits them in the way best 

 adapted for their preservation, 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 



* M. Kiiby, in his Monograph of the Bees of England, designates the two 

 anterior tarsi by the name of hands. The first joint is the palm, — palma. This 

 gentleman, in conjunction with M. Spence, has published a very complete and 

 detailed work on the elements of Entomology. 



t The generating organs of the male consists of au apparatas for the elabora- 

 tion of the semen, and of the parts proper to copulation. The preparatory ap- 

 paratus is composed of testes, vasa deferentia, and vesiculae seminales. The copu. 

 lating instrument is a penis provided with an armature consisting of surrounding 

 parts, of various forms, acting like pincers or forceps, with which the male seizes 

 the posterior extremity of the body of the female. The sexual apparatus of the 

 latter is composed of an ovary, the receptacle or calyx formed by its base and the 

 oviduct. For more minute details, see the memoirs of M. Dufour, Ann. des Sc. 

 Nat., and the Dissertation of Hegetschweiler, Zurich, 1820. 



:J; M. Audouin supposes, that, in a great number of Insects, the ova are fecun- 

 dated, as they descend, in a sac situated near the anus ; but this idea requires to be 

 confirmed by experiment, and one of those naturalists who have most closely studied 

 the anatomy of these animals, M. Dufour, is of a different opinion. 



