CHAP. 1. 1 DEFINITION WD STRUCTURE OF INSEt lS. 



5 



The antennae, .1 pair ol organs situated on the top or front of the 

 head, are movable at the will of the insei 1 and arc usual 1 

 threadlike appendages composed ol .1 variable number of joints. 

 The shape and relative proportions ol these joints arc very various 

 and in many families are ol great importance as a means of distin- 

 guishing between different groups of insects. The antennae con- 

 tain delicate olfactory bulbs and arc apparentl) also connected with 

 thefacultj of High t. The various shapes exhibited by the antennal 

 joints have caused the bestowal oi differenl names to indicate the 

 various structural types, and ol these the commonest are : 



setaceous, when the size ol the joints gradually decreases 

 to a point at the apex or tip, as is the case in Crickets. 



filiform, or threadlike, when the joints arc cylindrical and of 

 the same thickness throughout, as in many Carabidae and Termites, 



moniliform, or headlike, when the joints are globose, like head- 

 strung on a string. 



i 2. 3 1 



mm. hi types i il Anti in. lie 



I. Setaceous; Periplaneta amcricana (Blattidaef : J. Filiform; Cyrtacan- 

 thacris ranacea (Acrididael : .'.. Moniliform • Trachelizus politus (Brenthid«e) ; 

 t. Senate: Dorysthenes rostratus (Cerambycids) : 5, Pectinate; Gongy 

 lus gongylodes, male (Mantida ' : 6, Pluiw se ; Oixyi.i postica, male (Lymantri- 

 tdse): 7. Clavate; Episoiutts montanus (Curculionida : 8, < 1pi1.1t. : Rapala 

 jarbas (Lycaenidas) : ". Lamellate; Heliocopris bucephalus (Si 



serrate, or sawlike, when the joints arc triangular with a sharp 

 projecting anterior angle, liki the teeth ot a saw. 



