STRUCTURE AND CLASSIFICATION. 



21 



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 be filiform, 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 such a serrated form we pass gradually into the 



Fig. 8. 



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

 nate; e, clavate ; /, 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 bzpec- 

 ti7iated 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 



