186 MODERN CLASSIFICATION OF INSECTS. 



body is of a solid consistence, of an oblong, oval, and depressed 

 form {fig' 18. 1. Dorcus parallelipepidus $ ), with the head large, 

 especially in the males {^fig. 18. 2. head of the female of the same in- 

 sect). The basal joint of the antennae is very long, the following joint 

 being inserted obliquely at its extremity, so as to form an angle or 

 elbow. The eyes are often completely or partially divided on each 

 side by the lateral and acute margin of the head {fig. 18. 6.). The 

 immensely developed mandibles of the males in this family is one of 

 its most striking features ; these organs, in some instances (Chiaso- 

 gnathus, Pholidotus) equalling the entire length of the body. They are 

 capable of biting with very great force. The maxillae {fig. 18. 3.) 

 are generally terminated by a narrow membranous and ciliated lobe ; 

 sometimes, however, they are corneous and dentate ; the internal lobe 

 is also often terminated by a small curved spine. The mouth is closed 

 below by a large corneous plate, which Kirby and Spence hence regard 

 as the lower lip {labium), but which, from a comparative examination 

 of the lower parts of the mouth throughout the Lamellicoi'ns, ai^pears 

 decidedly to be the analogue of the mentum ; the parts which they 

 regard as the tongue, and which are two small membranous threads, 

 pencilled with hair, representing the true lip.* The figure 18. 4. re- 

 presents the lower organs of the mouth ivithin, the tips only of the 

 labial palpi extending beyond the front margin of the mentum 

 when the mouth is shut. It is at the base of these pencils of liairs, 

 and within the large plate which closes the mouth, that the labial 

 palpi, which are generally exserted^ arise. The fore-legs are generally 

 longer than the others, with the tibia3 toothed along the outer margin, 

 those of the female being shorter and broader than in the males. 

 The tarsi are cylindrical, and 5-jointed, with two strong terminal 



De Cervo volanti et ejus Hyhernacuh, Epist. Itiner. 78. cent. i. p. 12. t. i. Wolfen- 



butt. 1739. 

 Sadovski. Dissert. Passall (vide Bull. Sc. Nat. Oct. IS.Sl. vol. vi. ) 

 Perchcron, jMonogr. des Passales. Paris, 1835. 

 EschschoUz. Dissert. Passali, in Mem. Soc. Mosc. vol. vii. ; and see Ann. Sc. Nat. 



March, 1831. 

 Palisot de Beuuvois. Ins. d'Afr. et d'Amer. 

 And the general works of Fabricius, Olivier, Herbst, Jablonsky, &c. 



* See my ol)scrvations upon the comparative structure of the mouth of Cliiaso- 

 Tnathus Grantii, Mag. Nat. Hist. No. 26. 



