IXTRODUCTIOX. 



in the Carnivorous beetles they are usually sharply pointed and furnislied 

 with a cutting edge in order to enable them to seize and hold fast and cut 

 up their struggling prey ; in the plant-feeding beetles they are broad and 

 blunt, and more adapted for trituration than cutting ; the cavities at the 

 sides of the mandibles (in the Carabidse, &c.) have been before referred 

 to as termed the mandibular scrohes : these scrobes are often furnished 

 with single long setae, which seem to have much the same office to 

 perform as the siipra-orbital setae above referred to, and probably bear 

 some analogy to the whiskers of the feline tribe. Below the mandibles 



there is a second pair of hori- 

 Fig. 8. zontally moving jaws called the 



maxilhe ; these, taken in conjunc- 

 tion with the pa/2?e or antennal- 

 like processes that arise from 

 them, are of very great importance 

 in classification : the maxillae, as a 

 rule, are made up of the following 

 portions : — 1. The cardo or hinge, 

 Avhere the whole maxilla arti- 

 culates with the head ; 2. The 

 sHjyps or stalk articulated with the 

 cardo at a greater or less angle ; 



3. The palirifer or squama, the 

 support of the maxillary palpus, 

 the more correct term for which 

 would be the squama 'palpifera ; 



4. The lacinia or blade, which 

 may be regarded as the inner lobe 

 of the maxillae ; 5. The outer lube, 

 which in the Adephaga is usually 

 jointed (except in Cullistus and 

 one or two other genera) and 

 palpiforra, and is sometimes, as in 

 Dineutes, entirely absent ; 6. The 



maxillary palpus, which is usually shaped like an antenna, and is 

 generally 4-jointed, rarely 3 -jointed, and in Alcochara alone 5-jointed ; 

 these maxillary palpi vary very much in form and length : in the 

 Pselaphidai they are very large and curiously shaped ; in the Hydrophi- 

 lidae they are very long, being in fact much longer than the antennae ; 

 in the Curculionidae they are short, thick, and rigid. The floor of the 

 mouth is formed by the mentum : this is very variable in shape ; it is 

 usually more or less emarginate, and is occasionally furnished on each 

 sitle of the eniargination with a membranous border : these borders are 

 called the epilobes of the mentum. 



In front of the mentum is situated the ligida, which is sometimes 

 corneous, sometimes membranous, sometimes partly corneous and partly 

 membranous : it varies extremely in shape, and usually carries on each 



Uncler side of head of D. marginnlis. 



a. Mentum. 5. Linguiior ligula. c. Labinl 

 palpi, d d. Maxillary palpi (dissected out). 

 d^. Outer lobe. d'. Maxillary pal])us. cP. 

 Laciuia or blade (forming the inner lobe of 

 the palpi), d^. Palpifer or squama, d^. 

 Stipes or stalk, (i^. Cardo or hinge, e. Eyes. 

 /. Base of anteunaj. g. Throat, h. Mental 

 suture. 



