EXTERNAL STRUCTURE. 



usually sharp-pointed and furnished with a cutting edge in order 

 to seize, hold and cut up their living and struggling prey ; in the 

 plant and dung feeding beetles they are short, broad and blunt, 

 and adapted, as we might expect, for trituration rather than for 

 holding and cutting. These mandibles nearly always move hori- 

 zontally; a single exception occurs, however, in the Hhynehophorous 

 genus Balaninus in which they move vertically. Below the mandibles 



Fig. 1. — Head of Calosoma sycophcnita. V., vertex; Fr., frons: s.s., supra- 

 orbital seta ; o., eye ; g., gena or cheek ; antenna ; <■!., clypeus ; lbr. 9 

 labrum; md., mandible; p.m., maxillary palpus; i>.l., labial palpus. 

 (After Ganglbauer.) 



there is a second pair of horizontally moving jaws called the 

 maxillce ; as a rule, they are made up of the following portions : — 

 (1) the cardo or hinge, the piece by which the whole maxilla arti- 

 culates with the head ; (2) the stipes or stalk, following and 

 articulating with the cardo ; (3) the supporting piece of the 

 palpus, called the palpifer or squama palpigera * ; (4) the lacinia 

 or blade, with a cutting or triturating edge, which is regarded as 

 the inner lobe of the maxilla ; (5) the external or outer lobe or 

 galea, which may be jointed, entire, rudimentary, or even absent ; 

 (6) the maxillary palpus, which is usually shaped like an antenna, 

 and is generally 4-jointecl, sometimes 3-jointed, and very rarely (as 

 in Aleochara) 5-jointed. In the PsELAPHiDiE and HrDROPniLiDiE 



* As a matter of fact the palpifer appears to consist of two pieces, one 

 supporting the maxillary palpus, and the other the galea; the inner of these 

 pieces is therefore sometimes called the sub-galea. 



B 2 



