SECTION OP PENTATVTERA. 35 



4. If the turn are dilated and hilohed and the aiiteimcv clavate, the spe- 

 cies belou^s to the tribe of suout -beetles {Curculionida'), iu the tetraiae- 

 rous section, or the family of Erotylida', or that of Coccinellidfe, iu the 

 triinerous section. 



5. Beetles rcith distinctly serrate antenna; belong almost exclusively to 

 tlie families of Senicornes proper, iu the pentamerous section ; but this 

 rule also has a few exceptions. The pea and beau weevils {liruchida'), 

 in the tetramerous section, usually ha\e the antenna; decidedly serrate; 

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

 merous section {RJiipiphoridie and Pyrochroidcc)^ usually have the au- 

 tenna> serrate in the females, and tlabellate or branched in the males. 



(). All beetles tcith lamellate antenncv belong to the division of Lamel- 

 licornes proper, iu the pentamerous section. Oidy in very rare in- 

 stances the branches of a pectinate or ilabcllate antenna' are somewluit 

 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 

 ScolytidiTi. 



Section 1. PEKTAMERA. 



TJsxialhj five joints in aU the tarsi, one or tioo of them being sometimes deficient in very umall species.- aU 

 the joints Uiually slender and simple, eoceept that the anterior, or anterior and m,iddle tarsi are some- 

 times dilated and brush-like beneath, as a sexual distinction 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 iu this, and also iu 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 beneath with a dense 

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

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

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

 tarsi often give the clue to the dassilicatiou of snnill species in which 

 the number of the joints is delicient or difficult to be determined, ^'his 

 has been already more fully explained iu the general remarks ou pages 

 30 to 34. 



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

 in the males of certraiu species, can always be avoidetl 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 snuill species. 



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

 and the nature of theii" food, and distinguished primarily by the struc- 



