5oo 



THE STUDY OF INSECTS. 



of the external wall of the head are frequently referred to in descrip- 

 tions of beetles; these are the clypeus and the gula. The clypeus 

 (clyp'e-us) is situated on the dorsal side of the head, and is the sclerite 

 to which the labrum is attached. (Fig. 601, a, 5.) The gula (gu'la) 

 is the central portion of the ventral wall of the head, and is the part 

 which bears the labium (Fig. 601, b, 6). The sutures which bound the 

 gula, one on each side, are termed the gular sutures (Fig. 601, b,gs). 

 In the Rhynchophora the gula appears to be wanting, and there is a 

 single suture on the middle line of the head (Fig. 602, gs) ; in this case 

 the gular sutures are said to be confluent. The suture which separates 

 the clypeus from the sclerite immediately behind it (the epicranium) 

 is termed the clypeal suture (Fig. 601, a, cs). 



The Antenna. The more common types of antennae are named 

 and figured on page 60. But it is necessary to define two 

 other terms here. In many insects the first segment of the 

 antenna is long and the antenna is bent suddenly at the 

 joint between the first and second segments ; such antennae 

 are said to be elbowed <yc geniculate (ge-nic'u-late). In some 

 pectinate antennae the tooth-like processes are very long, 

 giving the antenna a more or less fan-like appearance ; such 

 antennae are defined ssflabellate (fla-bel'late) (Fig. 603). 

 FIG. 603. The Mouth-parts. The labrum and mandibles are suffi- 



ciently described on page 61. The parts of the maxillae are repre- 

 sented in Figs. 604, 605, and 606; of these there are five primary 



FIG. 604. Maxilla of Cicin- 

 dela. 



FIG. 605. Ventral aspect of 

 maxilla of Hydropkilus. 



FIG. 606. Dorsal aspect of 

 maxilla of Hydrofhilus. 



parts and three appendages. The primary parts are the cardo or hinge 

 (a), the stipes (sti'pes) or footstalk (b), the palpifer (pal'pi-fer) or pal- 

 pus-bearer (c), the subgalea (sub-ga'le-a) or helmet-bearer (e), and the 

 lacinia (la-cin'i-a) or blade (g). The appendages are the maxillary 

 palpus or feeler (d},\hzgalea (ga'le-a) or outer lobe or superior lobe 

 (/,/), and the digitus (dig'i-tus) or finger (h). 



