SECTION OF PENTAMERA. 35 



4. If the tarsi are dilated and hilohed and the antemiw clavate, the spe- 

 cies belongs to the tribe of snout- beetles {Curculionidw), in the tetrame- 

 rous section, or the family of Erotylidte, or that of Coccinellidae, in the 

 trimerous section. 



5. Beetles with distinctly serrate antentue belong almost exclusively to 

 the families of Serricoriies proper, in the pentamerous section ; but this 

 rule also has a few exceptions. The pea and bean weevils (Bruchidw), 

 in the tetramerous section, usually have the antenuse decidedly serrate; 

 and a few small families of the division of Trachelides, in the hetero- 

 merous section {Rhijpiphoridw and Pyrochroidw), usually have the an- 

 tenua? serrate in the females, and tlabellate or branched in the males. 



6. All beetles ivith lamellate aritemue belong to the division of Lamel- 

 licorues proper, in the i^entamerous section. Only in very rare in- 

 stances the branches of a pectinate or flabellate autenuaj are somewhat 

 flattened so as to resemble the true lamellate. An example of this is 

 found in the little beetles of the genus Phlceotribus in the family of 

 Scolytidse. 



Section 1. PENTAMERA. 



TTsually five joints in all the tarsi, one or two of them being sometimes deficient in very small speeies; all 

 the joints visually slender and simple, except that the anterior, or anterior and middle tarsi are some- 

 times dilated and brush-like beneath, as a sexual distinctioii of the males. 



It is seen by this formula that the pentamerous section is distin- 

 guished not only by the number, but also by the form and structure of 

 the tarsal joints, the tarsi in this, and also in the succeeding or hetero- 

 merous section being, with but few exceptions, slender and simple, and 

 clothed only with scattered hairs or bristles, whilst in the third and 

 fourth sections the tarsi are widened and covered beileath with a dense 

 brush of short hairs, or hair-like papilliP, and the penultimate, or last 

 joint but one, is almost always bilobed. It is important to bear this 

 two-fold distinction in mind, inasmuch as the form and structure of the 

 tarsi often give the clue to the classification of small species in which 

 the number of the joints is deficient or diflicult to be determined. This 

 has been already more fully explained in the general remarks on pages 

 30 to 34. 



The ambiguity arising from the dilation of some of the tarsal joints 

 in the males of certain species, can always be avoided by directing the 

 examination to the hindermost tarsi, which are never so dilated. 



This IS the most numerous section, and comprises, as a general rule, 

 the largest and most highly organized species in this order of insects, 

 though it also contains many small species. 



They can be divided into six sub-sections, founded upon their habits 

 and the nature of their food, and distinguished primarily by the struc- 



