OF NATl RAL HISTOHY. TS.'j 



nating before in a small triangular impression hotwetMi the an- 

 tennae ; the whole head, excepting the vertex, occiput and antenna;, 

 striate with close-set very small lines, which aro ratlur Inn-cr 

 on the mandibles: wings hyaline; nervurcsycllnwi.sh-hruwn ; miciH 

 cubital cellule none: anterior segment of the petiole deeply 

 striate [291] longitudinally each side, decidedly longer than the 

 second which is subemarginate above : abdomen ovul, truncate, 

 siibmurginate at base : pleura, striate like the head behind. 

 IjOiigth over three-tenths of an inch. 



■J, .Much more slender; transverse incisure between the wings 

 iiKirc obvious ; segments of the petiole not so deeply divided. 

 liCngth over three-twentieths of an inch. 

 Neuter, rieoous, varying to black ; abdomen cordate, almost 

 always black. 



liCiigth under three-twentieths of an inrh. 

 This species is very common in various parts of the United 

 States, even in houses, and may be observed, by every one, 

 going in procession. The radial cellule is slender and elongated, 

 the including nervures being nearly parallel ; the inner nervures 

 does not quite attain the edge. The first cubital cellule is hardly 

 larger than the discoidal cellule, the recurrent nervure of which 

 enters the first cubital at the middle. Second cubital extending 

 to the tip of the wing. 



2. M. coRRUGATA. — Honcy-ycllow ; wings with three complete 

 cubital cellules. 

 Inhabits Indiana. 



$ Body dark honey-yellow, almost piccous : antennae whitish ; 

 first joint not longer than the second and third together ; second 

 joint rounded, thickest : metathorax with two obtuse tubercles 

 instead of spines : wings hyaline; nervures and stignia pale yel- 

 lowish ; second cubital cellule complete, nearly as long a.** the 

 first cubital and petiulatcd from the apical angle of the diseoid.il 

 cellule, which is oblong subquadrate ; the descending nervure 

 from the stigma enters the .second cubital : abdomen, first [292] 

 j.iint somewhat gibbous at tip ; second segment rounded : feet 

 whitish. 



Length over three-twentieths of an inch. 



5 Somewhat darker than the male; mctathoracic tubercles 



l^o.").] 



