28 
ORDER OP COLEOPTERA. 
thorax. The epimeron of the mesothorax is very narrow in Harpalus, 
and scarcely distinguishable without the aid of a lens; but in a part of 
the long-horned beetles fSaperda, etc.) and in some others, it is consider- 
ably wider, and affords valuable characters in classification. The tro- 
chanters , or little joints at the base of the thighs, are marked T R in the 
figure, except the large hind trochanters, where the name is printed in 
full. Behind the metasternum, and extending outwardly from the hind 
coxrn is a narrow piece marked cx. p. This is the hind coxal ‘plate. 
This is a very narrow piece in Harpalus, but in some of the serricorn 
beetles (Buprestidce and E later idee), it is much wider, and furnishes im- 
portant generic characters, and in Haliplus, a genus of water beetles, it is 
excessively dilated. The other parts are sufficiently named in the figure. 
The antenna; of the Coleoptera are usually eleven jointed and of mod- 
erate length, but they are subject to much variation both in length and 
form, as will appear in the descriptions of the different families. The 
subjoined figures show their most common variations, and the names by 
which they are designated. These forms have been more particularly 
described on a former page, when treating of insects in general. 
il'ig- 4.] 
Antknnje of Colkoftkka. — 1, filiform or thread-shaped ; 2 ami 3, serrate or eaw-foothed ; 4, pectinate 
or comb-toothed ; 5, capitate or knobbed ; C, 7, 8, ciavate or club-shaped ; » and 10, lamellate or plated, 
—after Leconte. 
The palpi, or little jointed appendages to the mouth, also sometimes 
furnish important characters in classification. They vary chiefly in the 
shape of the terminal joint, which is sometimes much narrower than the 
others, when it is called acieular or needle-shaped, and sometimes much 
widened, so as to be in the form of a triangle or of a half-moon, or hatchet. 
As the terms large , small and medium-sized are often used in speaking 
of insects, and as these words vary considerably in force, when used in 
different relations, we give below their average meaning when applied 
to the Coleoptera: 
An inch or more in length, - \ery large. 
Three-quarters of an inch, Large. 
Half an inch, Medium. 
Quarter of an inch, Small. 
One-eighth of an inch or less, - Very small. 
The intermediate sizes are expressed by such phrases as rather large, 
rather small, or a little above, or a little below the medium, etc. This 
