1864.] 



u i 



% , but less developed. Length 5 lines ; expanse of wings 9 lines. 



Ffnh. — Rocky Mountains. Colorado Territory. 3 S , 65 $ specimen.s. 

 (Coll. Ent. Soc. Philad.) 



This pretty little species is closely allied to M. venpoides, the % being 

 almost an exact miniature of the % of that species ; but the $ differs 

 much in the markings ; those of the abdomen above being always con- 

 tinuous, and never interrupted, although often more or less emarginate 

 anteriorly, but never so deeply as to interrupt the bands; the general 

 form is much less robust in proportion to the size, than in vespoideg 9 • 

 The % differs from that of vespoufex in several points of structure, viz. 

 the club of the a«tennae is rounded and not flattened beneath, the basal 

 joint of the posterior tarsi is scarcely as long as the remaining joints, 

 while in vespoides % it is almost twice as long as the remaining joints; 

 the apical segment of the abdomen differs much from vespoides % , in 

 having no carinas on the disk, and in the tip being much more deeply 

 bifid, both above and beneath, and the projection on the third ventral 

 segment is more robust, and not compressed nor emarginate at tip as 

 in vespoides % . 



Mr. Ridings found this species in August, on a plant apparently 

 belonging to the genus Phacelia., growing in the vicinity of Empire 

 (■ity. The 9 9 were abundant, but the % % extremely rare. 



Masaris marginalis, n. sp. 



Female. — Deep opaque black, robust; head and thorax clothed with 

 short erect black pubescence, very finely and densely punctured ; orbits of 

 the eyes behind and on the upper part of the sinus in front, and a trans- 

 verse line or two spots between the insertion of the antennae, sometimes 

 interrupted so as to form a row of three or four spots, and sometimes 

 two spots with a minute spot above them, white ; clypeus large, rather 

 convex, slightly and obtusely emarginate at tip; labrum pubescent, and 

 sometimes tinged with piceous ; mandibles dull ferruginous at tip, as 

 well as the palpi more or less ; antennae shaped and colored as in the 

 preceding species. Thorax robust ; anterior margin of the prothorax 

 and its posterior margin, extending sometimes entirely to the tegulae. 

 sometimes interrupted and often abbreviated before reaching half way 

 to the tegulae, white; the anterior lateral white margin of the prothorax 

 is more or less developed, being sometimes reduced to a mere line (»r 

 spot, sometimes broad and entire and confluent with the posterior mar- 



