MASA11IS. 7 



bles, borders of labrum at base, a transverse ]ine at top of clypeus 

 and orbits of the eyes behind and over the emargination, yellow. 

 Anterior border of prothorax and sometimes also the posterior 

 edge, tegulae, a spot under the wings and the angles of the meta- 

 thorax, yellow. All the abdominal segments bordered by a wide 

 yellow band, the first beneath interrupted;* the three follow- 

 ing more or less emarginate in the middle, and with a blaek 

 transverse spot on eaeh side. Anal segment with two yellow 

 maculae. Feet yellow ; black at base. Wings a little grayish, 

 with basal and costal veins ferruginous. Radial cell having its 

 greater width in the middle of its length ; 2d recurrent vein in- 

 serted after the middle of the border of the 2d cubital cell. 



The yellow ornaments of % vary much in form and extent; 

 still more in 9 , the bands being of very different width, emargina- 

 tion, spots, etc, The bands are sometimes emarginated in middle, 

 and even interrupted on each side by the emargination. Some- 

 times the fascia at head and thorax are divided into several dots. 



Var. a. Sides of clypeus and labrum not margined with yel- 

 low ; no spot on the mandibles; a yellow spot at top of clypeus. 



b. No yellow spot beneath the wings, no spots on mesothorax. 



c. Metathorax with posterior angles slightly produced and 

 tipped with yellow. 



This insect differs from 31. marginalia by its very rough clypeus, 

 by the carina of the forehead, its depressed thorax, by the spines 

 of metathorax, etc. 



It has much resemblance to 31. vespiformis ; but the knob of 

 the antennae of the % is shorter; the projections of the 2d and 

 3d ventral segments are also differently constructed, that on the 

 2d segment of the American species being less developed and 

 bifid, while that of the 3d segment is strongly developed, bifid, 

 and bearing an acute spine behind. The antennae of the 9 are 

 very different ; the 1st joint being shorter than in M. vespiformis, 

 and the apex more swollen, as in Celonites. The color and dis- 

 tribution of the markings of 9 is also very different, M. vespi- 

 formis 9 having its ornaments rufous and much more developed. 

 Nevertheless the two species are so closely allied, that it is im- 

 possible to separate them generically. 



Inhabits Rocky Mountains, Tike's Peak. (Coll. Ent Soc. 

 Phila.) 



