COLEOPTERA. 423 



the second and succeeding joints make an angle with the first. 

 The mandibles are always well developed as chewing organs, 

 becoming abnormally enlarged in Lncauus, while in certain 

 Scarabeidse they are small and membranous. 



The maxilla? (Fig. 348) are supposed to prepare the food to 

 be crushed by the mandibles. The body of the maxilla con- 

 sists of the cardo ; a second joint, stipes, to which last are 

 attached two lobes and a palpus. In certain Oicindelidce 

 and Carabidce, the outer lobe is slender and two-jointed like 

 a palpus. The maxillary palpi are usually four-jointed, some- 

 times with one joint less, and in but a single instance is there 

 any additional joint, as in Aleochara. 



The meutum is generally square or trapezoidal, varying in 

 size. The labium bears the lignla, and supports the labial 

 palpi, and varying much in form, is thus important in classifi- 

 cation. The labial palpi are usually three-jointed, sometimes 

 two-jointed, or with no joints apparent, as in certain Stapliy- 

 linidm, according to Leconte. 



The greatly enlarged prothorax is free and very movable, 

 the pronotum or dorsal piece, considered to be formed origi- 

 nally of four pieces, is usually very distinct from the pieces 

 composing the flanks, though sometime they are continuous. 

 The two hinder rings of the thorax are covered up by the 

 wings and do not A'ary in form so as to be of much use in 

 classification. They are respectively composed of a pmescutum, 

 scutum and scutellum, and postscutellum, the first and fourth 

 pieces being more or less aborted. The pieces composing the 

 flanks are partly concealed by the great enlargement of the 

 dorsal parts of the segment, much more so than in the prece- 

 ding suborders, the side pieces being much smaller and more 

 difficult to trace ; and these flank-pieces (pleurites) help form 

 the under surface of the body, where in the I-Lpnenoptera, 

 Lepidoptera and Diptera, they are greatly enlarged, forming 

 the bulging sides of the body. 



The epimera and episterna of both the meso- and metatho- 

 rax, Lecoute states, are of much value in classification, especi- 

 ally those of the mesothorax, " according as they reach the 

 middle coxse, or are cut off from them by the junction of the 

 episterna with the metasternum." The thickened horny an- 





