574 PHILOSOPHY OF ZOOLOGY. 



pupa semicompleta. The insects in all the stages of life 

 live on the land. 



Among the Orthoptera, there are several genera with 

 their wings, when at rest, roof -like. These have either 

 the tarsi with four joints, as the Locustadse ; or the tarsi 

 have only three joints, as the Achetadae, including the ge- 

 nera Acheta, Truxalis, Ziphicera, Acrydium, and Pneu- 

 mora. 



In the remaining genera, the wings are horizontal. 

 Among these the Gryllidae, including Gryllus, Tridacty- 

 lus, an<} Gryllotalpa, have the body not flattened, nor the 

 sides truncated, but the abdomen is furnished with appen- 

 dages. In the genus Blatta, the abdomen is depressed, 

 and the sides truncated, with abdominal appendages. The 

 remaining genera, with horizontal wings are destitute of 

 the abdominal appendages. These are the Mantidae, in- 

 cluding Mantis, Empusa, Phasma, and Spectrum. 



Order IV. NEUROPTERA. 



The wings in this order are generally four in number, 

 wholly membranaceous, transparent, and greatly reticulated 

 by the anastomosing ribs. The under wings are either lar- 

 ger or longer than the upper ones. The labrum, mandi- 

 bulae, maxillae, and labium, are of the ordinary size, and 

 formed for cutting. There are two large eyes, and two or 

 three ocelli. The segments of the thorax are united, sup- 

 port the six legs, and are distinct from the abdomen. 



In some of the families, the antennae are about the 

 length of the head, subulate, and consist of from three to 

 seven joints, the last of which is setaceous. Among these 

 the Libelluladae, including Libellula, Aeshna, and Agrion, 

 have three tarsal joints, the mandibulae and maxii-ae corne- 

 ous, and the terminal ring of the abdomen, furnished with 



