312 LE CONTE.— LONGICORN COLEOPTEEA 



the following pages have been made to contribute greatly to this very desirable object. 

 Indeed, the genera Leptura and Strangalia might perhaps have been merged together, 

 since they only differ in the degree of prominence of the posterior thoracic angles; 

 this character is found to be variable, so that I have great doubt of its generic value. 



Whilst thus exposing the faults of the heretofore arrangements of this group, it is 

 by no means presumed that the present scheme is unobjectionable. All that is 

 claimed for it is, that it is more applicable to American species, as well as those 

 European species which commonly occur in collections. 



The large increase of genera may be objected to, no less than eight new ones 

 having been added to the Leptura alone, but these are recognized at once by certain 

 peculiarities of habitus, and the characters on which they are founded are, so far as I 

 know, invariable. The generic table appended to these remarks will render this 

 sufficiently obvious. 



There does not appear to be much accurate parallelism between the European and 

 American species of this family ; and most of the genera found in Europe are equally 

 developed on this continent. An exception to this principle is found in Rhagium, of 

 of which we have but a single species. Vesperus and Rhamnusium are peculiar to 

 the old continent, but here Desmocerus represents the former and Ceniroderus the 

 latter. Peculiar to America are Piodes, Gaurotes, and Typocerus, the five other new 

 genera are distributed over both continents. There are two species of this group 

 which are indigenous to Europe and America, viz : Acmceops strigilata and Strangalia 

 sexmaculata : they are confined to the Northern regions neither of them occurring 

 south of Lake Superior. 



The genus Distenia will be found among the CeramhycidcB. I know not why it 

 has been associated with the Leptura, with which its affinity is very slight : it is 

 much more closely allied to Ehuria and Cerasphorus. 



Before passing to the specific details of this tribe, it may be proper to say a few 

 words on the characters which distinguish the Leptura from other sections of the 

 Longicornia, and to ascertain the true value of the division which they form. 



Longicornia have been divided by Latreille, Serville, and other authors, into three 

 groups, Prionida, CeramhycidcB, and Lepturidce. The first group distinguished by 

 the deflexed labrum, rudimentary inner-maxillary lobe, and the antennge inserted in 

 front of the eyes. The second group has the head not narrowed into a neck and the 

 antennae are placed between the eyes. The third is separated on the single character 

 of the head being narrowed posteriorly into a kind of neck. The second group is 

 again divided into two : Ceramhycini, with porrected head and dilated palpi, and 

 and Lamiarii, with deflected head and piliform palpi. 



This arrangement is very unsatisfactory, since by following it, we associate with 

 Prioni, Asemum, Criocephalus, and other genera, which in form are true CalUdia ; 



