140 LE CONTE.— LONGICORN COLEOPTERA 



The second series contains genera having a large head, but the elytra are convex 

 and united ; the humeral angles are here wanting. This is the Dorcadion form. 



The third series contain genera of a flattened and usually short form of body, and 

 the head narrower than the thorax, which is rarely unarmed; the humeri are 

 prominent. This is the Acanthoderes or ^dilis form. 



It will be seen at once that there is no character given for distinguishing the first 

 from the third series, and my first effort after seeing the difference of these types in 

 nature, was to find characters invariable in each. After many patient dissections of 

 the mouth and trunk, I was compelled to rest the separation of these series upon the 

 form of the anterior acetabula. In so doing, I have discovered two genera which 

 separate themselves at once from all the others by the imperfection of the anterior 

 acetabula, which are widely open posteriorly. One of these (Dysphaga) is a Saperda 

 form, with narrow cylindric body ; the imperfection of the parts of the mouth, and 

 the shortness of the elytra show at once its embryonic position. The legs are very 

 short and weak, and the anterior tibise have but a mere trace of the oblique internal 

 groove found in all Lamise. It will be remembered that we have had already in the 

 Lepturidse a group with deflexed front, (also mostly with short elytra;) this, therefore, 

 is obviously one of the points of connection between the Cerambyci and Lamise, and 

 is likewise the lowest form of the series to which it belongs. 



The second of the genera with imperfect acetabula is a curious mixture of all 

 three of the series indicated above. From the Saperdse it borrows a cylindrical form 

 of body, from the second series its emarginate mandibles, and from the third a 

 peculiar oblique position of the thoracic spine. I regard it as belonging essentially 

 to the third series, although the most important characters of that series are wanting. 

 Yet its imperfect acetabula again indicate its embryonic character, and both the 

 cylindric body and the angle in the acetabula would indicate an inferior position in 

 the series to which it belongs. I regret that the want of specimens has compelled 

 me to postpone the examination of the parts of the mouth. In difficult cases like the 

 present, where it seems impossible to define entire series, the best that can be done 

 is to separate the embryonic forms by their embryonic characters, and then to 

 partition them among the groups to which they seem most naturally to belong. 



Having thus got rid of the embryonic forms, with incomplete acetabula, I found 

 that the typical (or first) series was distinguished by having the anterior acetabula 

 prolonged into a slight angle as far as the little stigma which marks the lateral 

 suture of the presternum ; and the coxa is visible through the fissure thus formed ; 

 the mentum is trapezoidal, and usually membraneous towards the apex. 



The remaining genera with prominent humeri constituting the third series, have 

 the anterior acetabula entirely round, the fissure present in the first series being 

 closed, to form a short suture leading from the little stigma to the margin of the 

 acetabulum. The mentum in this series becomes entirely corneous, and assumes a 



