THE EXTERNAL ANATOMY OF INSECTS 



41 



/ 



The Pedicel. — The pedicel is the second segment of an antenna {b). In 

 some insects it differs greatly in form from the other segments. 



The Cldvola. — The term cla- 

 vola is applied to that part of 

 the antenna distad of the pedi- 

 cel (c); in other words, to all 

 of the antenna except the first 

 and second segments. In some 

 insects certaia parts of the cla- 

 vola are specialized and have 

 received particular names. 

 These are the ring-joints, the 

 funicle, and the club. 



Tne Ring-joints. — -In certain 

 Fig. 51.— Antennaofachalcis-fly. j^^^^^g (g_g_^ Chalcididae) the 



proximal segment or segments of the clavola are much shorter than the suc- 

 ceeding segments; in such cases they have received the name of ring-joints (c'). 



The Club. — In many insects the distal seg- 

 ments of the antennae are more or less enlarged. 

 In such cases they are termed the club (c^). 



The Filnide. — The funicle (c^) is that part 

 of the clavola between the club and the ring- 

 joints; or, when the latter are not specialized, 

 between the club and the pedicel. 



The various forms of antennae are designated 

 by special terms. The more common of these 

 forms are represented in Fig. 52. They are 

 as follows: 



1. Setaceous or bristle-like, in which the 

 segments are successively smaller and smaller, 

 the whole organ tapering to a point. 



2. Filiform or thread-like, in which the 

 segments are of nearly uniform thickness. 



3. M'omliform or necklace-form, in which 

 the segments are more or less globose, suggesting 

 a string of beads. 



4. Serrate or saw-like, in which the segments 

 are triangular and project like the teeth of a saw. 



5. Pectinate or comb-like, in which the seg- 

 ments have long processes on one side, like the 

 teeth of a comb. 



6. Cldvite or club-shaped, in which the segments become gradually broader, 

 so that the whole organ assumes the form of a club. 



7. Capitate or with a head, in which the terminal segment or segments form 

 a large knob. 



8. Lamellate in which the segments that compose the knob are extended on 

 one side into broad plates. 



Wheit an antenna is bent abruptly at an angle like a bent knee (Fig. 51) it is 

 said to be geniculate. 



Fig. 52. — Various forms of 

 antennae. 



