238 NEWMAN ON THE 



will be observed that each of the remaining groups, in some of 

 their genera, copy, as it were, the quantity of surface and power, 

 as well as reticulation of wing, possessed by the Li bellulina. The 

 differences in the development of the pro- meso- and metathorax, 

 afford us steady assistance in the distribution of the circumferen- 

 tial groups. The Ephemerina possess the minimum degree of 

 prothorax and metathorax. The reverse is the character of the 

 Perliva ; in these we find the prothorax and metathorax of 

 considerable volume, though not the maximum degree, and the 

 mesothorax proportionally decreased. 



The Kphemerina and Perlina are thus placed in exact oppo- 

 sition to each other. From Ephemera we perceive very slight 

 difference in structure, if we pass to Nemoptenjx, thence to 

 Panorpa, and thence to Bittacus ; and the minute Boreiis is too 

 closely related to /*a«orjoa to be excluded. These four genera 

 constitute the Stirps Panorpina. The hind wings in this group 

 equal or exceed the fore wings in size. From the Panorpinn 

 we pass to another group, distinguished by a still greater de- 

 velopment of prothorax and metathorax, a less development of 

 mesothorax, a greater perfection of mouth, and a decided 

 necromorphous metamorphosis. This group includes the 

 Myrmeleonhm and Corijdallna of Mr. MacLeay. The larvae 

 are among the most singular productions of nature. They are 

 exceeding voi'acious, subsisting on the juices of other insects 

 which they kill : they conceal themselves on leaves, under 

 rubbish, or construct pitfalls in the earth. They have mandi- 

 bles perforated at the extremities, through which they suck the 

 juices of their victims. Raphiclia seems, in some degree, a 

 departure from the typical character of this group, its larvae, 

 according to Mr. Waterhouse, feeding on the bark of trees. On 

 this subject I cannot speak from observation ; but, if the 

 description is correct, it is a singular proof of the waywardness 

 of nature, which seems to defy our arbitrary laws. S'lalis has 

 a quiescent pupa. Thence we pass to Peria, or rather the 

 Perlina : here the metamorphosis is strictly isomorphous ; 

 the mouth strictly mandibulate, the pro- and metathorax fully 

 developed, and the mesothorax restricted. From the Perlina 

 we proceed to Emhia, thence to Termes, and from Termes to 

 Psocus. The Genus E7nbia exists without a history ; its 

 general habit points to Termes, as the type of its economy, but 

 at this we can only guess. The connexion between Psociis 



