576 PHILOSOPHY OF ZOOLOGY. 



usually termed case-worms. They change into a pupa in- 

 completa in the tube, which they inhabited when larvae, 

 and, when ready for exclusion, by means of the sheathed 

 antennae and fore and mid legs, they crawl out of the water, 

 throw off the covering, and become inhabitants of the land. 

 Dr LEACH has subdivided this class into two families. 

 The Leptoceridae have the antennae much longer than the 

 whole body, as Leptocerus and Odontocerus. The Phry- 

 ganidse have the antennas only the length of the body, as 

 Phryganea and Limnephilus. 



Order VI. HYMENOPTERA. 



The wings are four in number, membranaceous, and di- 

 vided into large unequal meshes by the anastomosing ribs. 

 The under wings are the smallest. The organs of the 

 mouth are adapted both for cutting and sucking. For the 

 former operation the labrum and mandibulse are sufficiently 

 strong ; while the maxillae are, together with the labium r 

 more or less produced, and by their union, form a sucker. 

 They have two labial and two maxillary palpi. The eyes 

 are large, and the ocelli three in number, ^he females are 

 armed with a sting or piercer. Many of the species live in 

 society, and exhibit, in the magnitude and regularity , of 

 their operations, the most striking displays of the attributes 

 of the social instinct. The insects of this order admit of a 

 division into two orders. 



I. HYMENOPTERA TEREBRANTIA. The females of this 

 order are furnished with a produced ovipositor, frequently 

 of sufficient strength to pierce solid bodies that the eggs 

 may be deposited. Among these, there are two families in 

 which the piercer is tubular, and does not consist of sepa- 

 rate valves. The Chr\ 7 sidae have the piercer formed of the 

 last rings of the body, retractile, and furnished with a 

 small sting, as Chrysis, Parnopes, and Cleptes. In the 



