COI.EOPTERA. HETEROMERA. 285 



by placing the Blelasoma at the head of the section, had evidently 

 in view their supposed relationship, with the Lamellicornes, which 

 cannot here be adopted in linear classification, the Lamellicornes 

 being placed at the head of the stirps of Chilognathiform Pen- 

 tamera. A similar difficulty, also, here exists; because, by considering 

 the Stenelytra as following the Trachelides, and as being succeeded 

 by the Taxicornes and Melasoma (which would thus be placed at 

 the end of the section), we are unable to make the Salpingidae 

 (amongst the Stenelytra) the means of uniting the Heteromera and 

 Pseudotetramera, the latter having the Curculionidc-c at its head, with 

 which, indeed, the Melasoma have no affinity. This kind of diffi- 

 culty is the necessary result of endeavouring to exhibit, in a linear 

 series the intricate affinities of this extensive order of insects. 



The typical genera, mentioned above, seem to be equivalent with the 

 rank of the Linnaean genera, and are, consequently, to be regarded as 

 modern families terminating uniformly in idse. 



By uniting the Xystropides of Solier (CistelidEe) with the Sclerop- 

 terides, the Heteromera are divisible into two primary groups, nearly 

 corresponding with Latreille's two primary sections indicated above, 

 although some of Latreille's secondary group, Stenelytra, are evidently 

 more intimately allied to the second primary group than to the first. 

 These two primary groups are very difficult to characterise, and the 

 following definitions must be regarded only as approximating to 

 precision. As they do not precisely correspond, either with the di- 

 visions of Latreille or Solier, I have thought it necessary to sub- 

 stitute other denominations. 



In the first of these tribes, wliich may be named Trachelia, 

 (nearly corresponding with Latreille's Trachelides and Solier's Eus- 

 chionidcs), the head is generally considerably dilated behind the eyes, 

 and then suddenly narrowed, the prothoracic cavity not equalling in 

 breadth the broader part of the head, which is thence exposed. The 

 insects are generally of gay colours, flying and running with agility by 

 day, and hence the fore-legs are organised for quick motion by having 

 the coxiK elongated. 



In the second of these tribes, which I name Atrachelia, (nearly 

 corresponding with Latreille's first primary division, and with Solier's 

 Scleropteridcs and Xystropides, the prothoracic cavity is as wide 

 as the broad part of the head, the hinder part of which is con- 

 sequently immersed up to the eyes ; the insects are often of dull and 

 obscure colours, seldom appearing by day (except in those species 



