X INTRODUCTION. 



membranous, or coriaceous, instead of horny like the rest of the 

 surface. The upper surface is divided into regions, the back part 

 being called the occiput, the middle the vertex, and the anterior 

 the front ; on each side are the eyes. 



The eyes of Coleoptera are very variable in form and shape, 

 and are composed of aggregated small lenses; rarely they are 

 entirely wanting ; ecpially rarely accessory eyes are seen, in the 

 form of one or two simple lenses ; they are situated between the 

 compound eyes, on the upper surface, and are called ocelli. 



The under surface of the head is widely excavated, forming the 

 mouth ; the parts beneath the eyes and behind the mandibles are 

 called the genas; behind the mouth the region is called the throat, 

 or gula ; the suture separating the gula from the mention (here- 

 after described) is called the gular suture ; from the opening of 

 the mouth may be seen two sutures, which sometimes unite at the 

 medial line, running backwards ; these are called buccal sutures; 

 they are of but small interest in classification, but I have made 

 use of their position to define the groups of the sub-family Tele- 

 phoridee. 



Antenna. — The antennae are articulated appendages inserted 

 in front of, or more rarely, between the eyes — usually under the 

 side margin of the front ; they vary in form and number of joints, 

 the latter attaining, in our fauna, the minimum in Adranes, of the 

 family Pselaphidse, in which genus they consist of but two joints ; 

 the maximum is reached in certain species of Prionus, of the 

 family Cerambycida?, where 25 — 27 joints are seen. The usual 

 number of joints is eleven ; the joints nearest the head are usually 

 of denser consistence than the outer ones, which possess a peculiar 

 structure, intended for special sensibility. It consists in an im- 

 mense number of pores, visible only under a very high magnifying 

 power, and covered by a very delicate transparent membrane. 

 These pores vary in situation in different families, but it is not 

 yet known how far these variations may be used for purposes of 

 classification. Lacordaire has found them of service in grouping 

 the genera of Buprestidae. 



The forms of antenna? may be reduced to the following types : — 

 1. Filiform, where the joints are cylindrical, and the outer 

 ones are not, or scarcely enlarged ; when the outer ones are some- 

 what more slender, the antennae are said to be setaceous. 



