1903.] NATURAL SCIENCES OF PHILADELPHIA. 225 



twice as long as broad; in profile the anterior and posterior slopes of 

 the node are of nearly equal length, the former slightly concave, the 

 latter distinctly convex, the apex somewhat flattened. Postpetiole 

 hardly more than half as long as the petiole, but half again as broad, 

 with prominent, rounded anterior angles and convex node. 



Head subopaque, longitudinally reticulate rugose, mandibles and 

 frontal area smooth, clypeus with several longitudinal rugse, which are 

 so delicate as to leave the surface shining. Thorax subopaque, irregu- 

 larly reticulate rugose, especially on the pronotum and epinotum, 

 the neck and pleurae still more delicately reticulate. Petiole and post- 

 petiole subopaque, delicately reticulate rugose. Gaster smooth and 

 shining. 



Hairs on the head and trunk whitish, rigid and obtuse, but hardly 

 clavate, longest and most conspicuous on the aljdomen. Antenna and 

 legs clothed with delicate, appressed, whitish hairs. 



Color yellow, whole head, except the mandibles, dark -brown. There 

 is a large brown blotch on the pronotum and one on the epinotum. 

 Nodes of petiole and postpetiole, trochanters, swollen portions of the 

 femora, club of antennae and the dorsal surface of the gaster distinctly 

 infuscated. 



Type locality: Boulder, Colo. 



Described from a dozen specimens received from Rev. P. J. Schmitt, 

 O.S.B. 



This variety appears to be identical with the form mentioned by 

 Emery from Hill City, S. Dak. (Pergande). It differs from specimens 

 of the typical European miiscorum, sent me by Prof. Forel from the 

 Schluderbach, Switzerland, in the following points: Hairs on the 

 trunk distinctly shorter and at least on the head, thorax and pedicel 

 distinctly thicker. Dorsal portions of thorax and pedicel and the 

 thickened portions of the femora infuscated. These characters are 

 constant in the twelve Colorado specimens. 



3. Lepto thorax acervorum Mayr, subs, canadensis Provancher. 



L. canadensis Provancher. Addit. Faun. Canada, Hynienopt., 1SS7, p 



245. §$c?. 

 L. acervorum var. canadensis Er. Andre, Rev. d'EntomoL, A I, 1887, p. 



295. ^ . 

 L. acervorum var. canadensis Dalla Torre, Catal. Hvmenopt., VII, 1893, 



p. 123. 

 L. canadensis Emerv, Zool. Jahrb. Abth. f. Svst., VIII. 1894, pp. 317, 



318, 319. 



Worker (PI. XII, fig. 4). — Length 2.75-3.5 mm. 

 Minute ocelli occasionally present. Cl3^peus with a distinct longi- 

 tudinal impression in the middle, its anterior border rather convex and 

 15 



