82 THE CANADUN ENTOMOLOGIST, 



Horn " Classification," though the tables are constructed on a different 

 plan and on account of the limits of the fauna it has been possible to do 

 away altogether with the use of certain characters difficult of observation. 



The prothorax in the Longhorns offers two principal types : that in 

 which the lateral edge is sharp or thin for almost or quite the whole 

 length, more or less toothed, giving us the form called margmed, and 

 that where it is cylindrical or rounded on the sides, which may, however, 

 be either spined, tuberculate or plain. Thus we have a point of depar- 

 ture for sub-family separation, which may be aided by taking into account, 

 among those genera in which the thorax presents the second form, a 

 study of the palpi. These may have the terminal joint more or less com- 

 pressed or subtriangular as in the Cerambycinse, or this joint may be 

 cylindrical and pointed at tip as in the Lamiinoe. The front tibise in the 

 latter group have an oblique sulcus or groove on the inner surface, not 

 always very distinct, but to be seen without difliculty in the larger species 

 like Monohavimus ; once seen it may be used with some facility elsewhere. 

 In the Cerambycinee this groove is wanting. 



Following the Classification, we may, then, throw the characters into 

 tabular form, separating three sub-families, thus : 

 Prothorax margined, antennae not pubescent, labrum connate with the 



epistoma PRiONiNiE. 



Prothorax not margined, labrum free. 



Front tibife not grooved ; last joint of palpi not acute at tip, often 

 subtriangular Cerambycin^. 



Front tibia with an oblique groove on the inner side ; palpi with last 



joint cylindrical, pointed at tip Lamiin/E. 



The Canadian species of the first sub-family, the Prioninte, are but 

 three in number and represent as many genera. All of them are of rather 

 large size, brown colour, and with elytra of a leathery appearance. The 

 genera may be distinguished thus : 

 Sides of prothorax two- or three-toothed. 



Form elongate, parallel ; antennte more slender, joints not overlap- 

 ping Orthosoma. 



Form stout ; antenn;* heavy, joints overlapping, especially in the 



male Prionus, 



Sides of prothorax with one tooth, antennas slender Tragosoma. 



