EXTERNAL ANATOMY OF INSECTS. 403 
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*. Again, they have no 
proper Enarthrosis, or ball and socket; though the an- 
terior coxe of the Capricorn-beetles (Longicornia Latr.) 
approach very near to this kind of articulation, as will he 
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. 
of insects, they have some motion; whereas a suture is an articu- 
lation without movement. Jdid. 
a Their connexion by means of a ligament classes them under 
Syneurosis (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. 1. 126), and those of the abdomen, which 
are capable of larger movements, to’ Diarthrosis (Ibid. 127). 
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