238 CLASS INSECTA. 



intermediate tarsi, as in the 0. Melange^ is alone sensibly 

 dilated. 



Omopheon, Lat. iScolytus, Fab. 



This sub-genus is composed of a small number of species 

 which are found on the banks of waters in Europe, in North 

 America, in Egypt, and at the Cape of Good Hope. M. 

 Desmarest has described the larva of the most common spe- 

 cies. Its form approaches that of the larva of dytiscus. The 

 anatomical observations of M. Dufour appear to confirm 

 these relations. 



The others, whose body is tolerably thick, have very large 

 and projecting eyes ; antennas thickening a little towards 

 their extremity, and composed of short articulations, for the 

 most part in the form of a reversed cone. One of the two 

 spurs of the internal extremity of the two anterior legs is 

 inserted more high than the other, with a notch between. 

 The first three or four articulations of the anterior tarsi of 

 the males are but little dilated in the majority. The palpi 

 are never elongated. These insects inhabit the neighbour- 

 hood of rivers, and all belong to Europe or Siberia. 



Sometimes the labrum is very short, transverse, and ter- 

 minated by a right line. The last articulation of the exter- 

 nal palpi is almost in the form of a reversed cone, thicker, 

 and more truncated at the end. The mandibles advance 

 remarkably beyond the labrum. The anterior tarsi of the 

 males are sensibly dilated. 



Elaphrus, Fab. Elaphrus, Blethisa, Pelophila, Dej . 



Some, and the largest {B/ethisa, Bonelli), have the corslet 

 more broad than long, plain, bordered laterally, almost 

 square, and a little contracted towards the posterior angles. 



In one set the first three articulations of the anterior tarsi 

 are strongly dilated, and cordiform in the males. These are 



