THE COCKROACH 173 



it bears a patch of closely set, short bristles. The lacinia has a 

 number of long, sharp bristles on its inner border, and terminates 

 in two claw-like teeth or hooks. It is used to help the mandibles 

 in masticating the food. Behind the first maxillae is the labium, 

 or lower lip. This is composed of the two second maxillae, united 

 together in the middle line so as to form a flattened plate behind 

 the mouth. The union affects only the portions which corre- 

 spond to the cardines and stipites of the first maxillae, called 

 respectively the submentum and mentum ; those representing 

 the galeae and laciniae remaining free. On each side of the labium 

 is a 3- jointed palp. 



The first thoracic segment (prothorax) is large, and, as already 

 mentioned, forms a protecting shield over the head. The second 

 and third segments (meso- and metathorax) are smaller and 

 softer ; and, in the full grown male, carry each a pair of wings. 

 The front wings are rather hard and horny, and serve as covers 

 to the hind pair rather than as organs of flight. The anterior 

 part of the hind-wings is moderately rigid, so as to present a good 

 cutting edge to the air, but the posterior portions are very thin, 

 and when at rest are folded fanwise beneath the anterior part, 

 and the entire hind-wing in turn is placed beneath the wing-cover 

 (front wing). The females of the common cockroach are wingless, 

 these appendages being represented merely by small triangular 

 flaps ; but in the larger American cockroach wings are present 

 in both sexes. 



Each segment of the thorax carries one pair of legs, of which 

 the hindmost is the largest, the anterior the smallest. The first, 

 or coxal, joint is large and much flattened, so that it can be closely 

 applied to the ventral surface of the thorax, and thus present 

 no obstacle to the passage of the insect along narrow crevices. 

 The trochanter (second joint) is very small, and is followed by 

 the femur and tibia, whose surfaces, especially those of the latter, 

 are covered with stiff projecting bristles. These bristles are 

 used as scrapers or combs in cleansing the body from dust and 

 other foreign matter. The tarsus consists of six joints. On the 

 lower side are soft white patches, resembling velvet, which pre- 

 vent the foot from slipping on smooth surfaces. The last joint 

 carries two sharply curved claws, and between these is a pad, 



