28 



ORDER OF 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 

 coxae is a narrow piece marked ex. p. This is the hmd coxal plate. 

 This is a very narrow piece in Harpalus, but in some of the serricorn 

 beetles ( Buprestidm and Elateridw), it is much wider, and furnishes im- 

 portant generic characters, and in Halii^lus, a genus of water beetles, it is 

 excessively dilated. The other parts are sufficiently named in the figure. 

 The antennce 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. 



[Fig. 4.] 



ANTENN^ffi; OF COLEOPTHRA.— 1, filiform or thread-sbaped ; 2 and 3, serrate or saw-!«othed ; 4, pectinate 

 or comb-toothed ; 5, capitate or knobbed ; 6, 7, 8, clavate or club-shaped ; 9 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 acicular 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, .... Very lg,rge. 



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 



