THE CANADIAN ENTOMOLOGIST. 189 



small yellow basal ring ; last joint cylindrical, truncate on tip ; labial 

 about as long, second joint arcuate, thin, enlarged on tip ; last joint of 

 the same length, subarcuate, largely fusiform above, shining black, tip 

 thinner, yellow. 



Antennae a little shorter than head and thorax, clavate, dull black, 

 more or less annulate with yellow, basal joint above yellow, below the 

 basal joints shining black. 



Head broad ; vertex transversally ovoid, elevated ; anteriorly finely 

 rugose ; a number of very fine elevated lines originating together between 

 the antennae, and then diverging ; the color and pattern of the vertex 

 varies much ; the main color is dull black, with a yellow transversal band, 

 which is entire or more or less divided and may be wanting entirely ; two 

 pitchy black transversal bands are divided by a middle longitudinal band, 

 consisting of two anterior and two posterior approximate twin spots, all 

 these pitchy black shining flat spots and bands may be differently shaped ; 

 besides there is on each side near the eyes on the vertex a posterior 

 linear flat spot, and another behind this on the occiput ; the yellow trans- 

 versal band fills the space between the two pitchy black bands, and is 

 always interrupted in the middle by longitudinal band ; the yellow band 

 is entirely wanting in the N. England, Michigan and N. York specimens, 

 it is more or less indicated in the specimens of the Southern States, and 

 always present in the Western States and Colorado. 



Prothorax short, nearly once broader than long ; sides about straight ; 

 front margin semi-circular, dull brown ; the front margin, two large spots 

 on the part before the transverse sulcus, and two smaller ones after the 

 sulcus, and the membrane between the prothorax and mesothorax luteous 

 or yellowish ; some black hairs on the sides of prothorax ; thorax pitchy 

 fuscous to black above and below : the margins sometimes a little 

 luteous 



Abdomen of female much shorter than the wings ; of the males less 

 shorter and more slender ; pitchy black ; the basal half principally of the 

 females or newly transformed specimens with a large dull luteous spot, 

 covered with short and fine whitish villosity. 



Female genitals the same of M. mobilis, but the black appendages a 

 little shorter and thicker, with very long black hairs ; male genitals similar, 

 but the spoon-shaped part a little shorter. 



