OF AMERICA NORTH OF MEXICO. 



313 



while Distenia, although strongly resembling Cera^^plioncs, is put among Lepiurce. 

 Again, there are many true Ceramhjd, (e. g. Itenopterus,) which have the head 

 elongate and porrected : Necydalis likewise has the head suddenly contracted behind 

 precisely like Tozotus, while the front is deflected and the palpi filiform ; so that it 

 becomes difficult to determine whether the genus belongs to the Lepturce, Ceramhy ci 

 or Lamia. 



So fallacious are the received characters, that a genuine Saperda-iox'CCi with 

 abbreviated elytra, has been described both by Newman and Haldeman as a 

 Molorckus, (Thia, Nm., Tessaropa, Hald.) and another genus {Encylops, Nm.) allied 

 to Necydalis, has been placed near Toxotus. A new genus from Georgia has a 

 remarkable resemblance to Dorcadion, whilst the head is prolonged behind the eyes, 

 and its true affinity is with the gibbous Ciyti. It is thus plainly seen that these 

 divisions so distinct in nature, have not yet any natural distinctions in our systems. 



Dr. Zimmerman has recently recognized the importance of a character heretofore 

 neglected, and through his kindness I am enabled to make use of it in the present 

 essay. He finds that in all Lamia-ioxms, the anterior tibise have an oblique sulcus 

 internally, which in many cases becomes so deep as to form an emargination, such as 

 IS observed in most Carabica. This character, with a single exception, is wanting in 

 all other Longicornia. Making use of it and at the same time suppressing the 

 primary group Leptura, as not possessing sufficiently distinct characters, we obtain 

 three great divisions which embrace all Longicornia. 



1. LAMItE. 



TihicE anticse intus oblique 



sulcatae. 

 Palpi semper filiformes. 

 Antenna verticales. 

 Thorax immarginatus. 

 Cox<B anticse globosse. 



2. CERAMBYCI. 



Tibia intus non sulcatse. 



{Michthysomate excepto.) 

 Palpi ssepissime compressi. 

 Thorax immarginatus. 



3. PRIONI. 



TibicB intus non sulcatae. 

 Palpi compressi. 

 Antenna frontales. 

 Coxa anticse valde trans- 

 versae. 



The Cerambyci may again be divided into three groups according to the form of 

 the anterior coxse and tibise. 



1. LEPTURID^. 



Tibia filiformes. 

 Ccza anticse conicse. 



2. CERAMBYCID.E. 



Tibia filiformes. 

 Coxa anticse vel globosse vel 

 subtransversse. 



3. SPONDYLID.E. 



Tibia anticse compressse. 

 Coxa anticse subtransversse. 



