284 NATURAL ARRANGEMENT OF INSECTS. 



armature of the joints themselves ; in which case Enoplo- 

 cerus, Macrotoma, and others,, would also have serrated 

 antennae, as each joint is thickly set with minute teeth. 

 In Polyarthron they are flabellated, and consist of forty- 

 seven joints ; whereas, as we have before had occasion 

 to observe,, the typical number,, as that which most con- 

 stantly occurs, is for the organ to consist of but eleven. 

 We however find in this family frequent aberrations in 

 this particular, as very many exceed the usual number. 

 Its most elegant form is that, perhaps, which occurs in 

 the imbricated antennae of the males of Prionus; and 

 the family has received its name from this serrated struc- 

 ture, prion signifying a saw. Other parts, besides the 

 antennae, are likewise thus singularly furnished, espe- 

 cially the legs and sides of the thorax ; the latter being 

 always armed, laterally, with one or more spines, and 

 frequently with a row of very minute and sharp teeth ; 

 and it is from the variation in the number and arrange- 

 ment of these spines and teeth, that Serville has founded 

 his distribution of the large mass they constitute, and 

 has thence broken them into genera. We have adverted 

 to the characteristic of their being usually dark and 

 sombre insects. This must not, however, be adopted 

 with a rigorous application ; nor can, indeed, any cha- 

 racter universally in any group in nature ; for here, even 

 in JHfegopis, Anacantha, and Ccelodon, the thorax is not 

 denticulated ; in Mallodon, and many others, the legs 

 are not serrated ; in Anacolus and Pcecilosoma, the body 

 is gaily coloured; and in Pyrodes, Psalidognathus, 

 and Clieloderus, it is brilliantly metallic : the latter is 

 remarkable for its concave, small thorax, and is an ex- 

 tremely rare insect from Mexico, whence also Psali- 

 dognathus comes. There is considerable difference in 

 the sexes of the latter ; and, as in most metallic insects, 

 differences of colour, some being of a deep blue, and 

 others of a bright green ; whereas Cheloderus is of a rich 

 vinous tint. The leading instance of analogy to the Luca- 

 nidaK is found in the deflexed, elongated, forcipate man- 

 dibles of the former ; but the largest developement of 



