EHYNCHOTA. 567 



by the labium, is a three- or four- jointed almost closed tube, which is 

 narrowed towards the point, and is covered at the larger open base by 

 the elongated three-cornered upper lip. The antennae are either 

 short and three-jointed with a setiform terminal joint, or are 

 many- jointed and often elongated. The eyes are small and usually 

 facetted, but they are sometimes ocelli with a simple cornea. 

 Frequently two ocelli are found between the facetted eyes. The 

 prothorax is usually large and freely moveable, but all the thoracic 

 segments may be fused together. Wings are sometimes quite absent ; 

 usually four, rarely two, are present. In the first case the front 

 wings are horny at the base and membranous at the tip (Hemiptera), 

 or the front and hind wings are similarly formed and are membran- 

 ous (Homoptera), though the anterior are often stiffer and coriaceous. 

 The legs are, as a rule, adapted for walking, but sometimes they 

 serve for clinging or swimming. In other cases the front legs are used 

 to capture prey, or the posterior for springing. The alimentary 

 canal is distinguished by the numerous salivary glands, and by the 

 complicated chylific ventricle, which is often divided into three 

 regions ; behind the chylific ventricle usually four Malpighian tubes 

 open into the hindgut. The ventral cord is concentrated into three, 

 usually into two thoracic ganglia. With exception of the. Cicada, the 

 female genital organs have only four to eight egg-tubes, a simple 

 receptaculum seminis and no bursa copulatrix. The testes are com- 

 posed of two or more tubes, the ducts of which are usually dilated 

 at the lower end. Many (bugs) emit an offensive smell, which pro- 

 ceeds from the secretion of a gland placed in the mesothorax or 

 metathorax, in the latter case opening between the hind limbs. 

 Others (Homoptera) secrete by means of numerous cutaneous glands 

 a white waxy film which covers the surface of their body. They all 

 live on vegetable or animal juices, to which they obtain access by 

 means of the piercing styles of their rostrum. Many of them, by 

 their appearance in great numbers on young plants, are harmful, and 

 sometimes cause gall-like outgrowths; others are parasitic on animals. 

 The young, when hatched, possess the form and habits of the sexually 

 mature animal. They have, however, no wings, which make their 

 appearance as small stumps after one of the first moults. The true 

 Cicada need several years to effect their metamorphosis. The male 

 Coccidce change inside a cocoon to quiescent pupae, and undergo 

 accordingly a complete metamorphosis. 



Sub -order 1. Aptera=Parasitica, Wingless Rhynckota, with short 

 fleshy rostrum and broad cutting styles. Sometimes they have 



