404' EXTERNAL ANATOMY OF INSECTS. 



the esoderma, or skin, above noticed as lining the inte- 

 gument, and all admitting a degree of motion more or 

 less intense, rather afford examples, as the case may be, 

 of other kinds of articulation a . Again, they have no 

 proper Enarthrosis, or ball and socket; though the an- 

 terior coxa? of the Capricorn-beetles (Cerambyx L.) ap- 

 proach very near to this kind of articulation, as will be 

 shown more fully in another place. The inosculating 

 segments or rings, which distinguish the abdomen, and 

 sometimes other parts of insects, are an example of a 

 kind of articulation not to be met with in the Vertebrata. 

 The ginglymous articulation, in which the prominences 

 of the ends of two joints are mutually received by their 

 cavities, and which admits only of flexion and extension, 

 often prevails in the limbs, &c. of insects ; but in many 

 cases the joints are merely suspended to each other by a 

 ligament or membrane ; and, in fact, the integument of 

 insects, with regard to its articulation, even where the 

 joints ginglymate, may be said in general to consist of 

 pieces connected by the internal ligament, membrane, or 

 skin that lines it; for even in the legs, where the gingly- 

 mous articulation is sometimes very remarkable and 

 complex, as will be shown to you hereafter, the joints 

 are also connected by this substance, as you may see if 

 you examine the legs of any Coleopterous insect. 



insects, they have some motion ; whereas a suture is an articulation 

 without movement. Ibid. 



a Their connexion by means of a ligament classes them under 

 Synneuros-is (Monro On the Bones, Dr. Kirby's edit. 29), but even 

 this not strictly, since a common ligament connects them all. Those 

 of the trunk, as admitting a slight degree of motion, belong to Am- 

 phiarthrosis {Anat. Compar. i. 126), and those of the abdomen, which 

 are capable of larger movements, to Diarthrosis {Ibid. 127). 



