STRUCTURE AND CLASS //'VCATION. 2i 



mon types of antennal structure, which occur in all insects, that 

 they may be referred to hereafter without especial description. 



The antennae are said to heji/i/onn, or thread-like, when the 

 joints are nearly even throughout, cylindrical, tolerably equal in 

 length, and similar in general appearance. A serrate or saw- 

 toothed antenna has the joints more or less triangular in shape 

 and so fitted that one margin resembles the toothed edge of a 

 saw. Quite frequently antennae of this type are distinctly flat- 

 tened. From sucli a serrated form we pass gradually into the 



Fig. 8. 



Antennal types. — a, filiform and pubescent ; A, serrate ; c, singly pectinate; d, bipecti- 

 nate ; e, clavate ; y, capitate; g, geniculate; h, lamellate. 



pectinated or comb-toothed type, where the joints are furnished 

 laterally with processes of variable length. When both sides of 

 the joints have these processes the antenna is said to be bjpec- 

 tifiated or feathered ; when the processes become very slender, 

 almost hair-like, and exceedingly numerous, it is said to be 

 plumose. A feeler is clubbed, or clavate, when the joints toward 

 or at the tip suddenly or gradually enlarge to form a more or 

 less evident club or bulb, and this type is widely distributed in 

 all the orders, a variety of terms being in use to indicate the 

 particular form of the club. A lamellate feeler has at its tip a 

 series of elongate, flattened or leaf-like joints, usually applied 

 close together to form a solid mass that conceals and protects 



