AMERICAN HYMENOPTERA. 105 



neath; the apical joint the longest, joints three and four equal. Dor- 

 sulum shining, with distinct, separate punctures; mesopleura; striated 

 under the tegulae, the rest rugose with a tendency to striation. Scu- 

 tellum sculptured like the dorsulum, at the sides depressed but not 

 so^ strongly so as in argentine. Metanotum punctato-rugose, in the 

 middle with a shallow indistinct channel; metapleurae striated; pos- 

 terior face rugose, at the top with a distinct V-shaped fovea; not 

 strongly defined laterally. Legs not quite so robust as in argentine. 

 Venation like argentine except there is no indication of a cross first 

 tran. cu. Abdomen shining, impunctate, not constricted between the 

 segments. Color black; anterior tibia; beneath and at the base, their 

 tarsi, base and apex of the four posterior tibiae, and their tarsi 'some- 

 what, brownish-yellow. Tegulae in front and the palpi yellowish. 

 Wings clear hyaline, iridescent, venation black. With the usual 

 facial pubescence. 



Habitat.— Florissant, Colorado, alt. 8,100 feet (S. A. Roh- 

 wer), June 10 and 11, 1907, on foliage of Ribes vallicola. 



Diodontus vallicola- is close to argintinas, but is smaller, the 

 metathorax is not margined laterally by strong carina,' the 

 ocelli are in less than an equilateral triangle, the front is more 

 coarsely sculptured and the front is depressed, etc. 

 Diodontus vallicolae salicis n. subsp. 



Male.— Length about 4 mm. Differs from the typical vallicola: in 

 not having the front so strongly depressed, the cheeks hardly striated 

 the dorsulum more densely punctured, scutellum not so depressed at 

 the sides, metanotum not channeled above, and the legs more yellow. 



Habitat.— Boulder, Colorado, April 11, 1908 (S. A. Rohwer), 

 on foliage of Salix exigua. 



Diodontus cockerelli n. sp. 



Male.— Length 2.75 mm. Slender. Labrum broadly emarginate 

 lobes small, triangular. Clypeus apparently without teeth or an 

 emargmation. Front shining, very finely closely punctured; vertex 

 and cheeks with some large punctures; frontal line distinct but not 

 strong. Head not depressed between the eyes, seen from above it is 

 straight m front. Ocelli in less than an equilateral triangle the dis- 

 tance between the lateral ocelli about the same as the distance from 

 one of them and the nearest eye margin. Antennaa long, slender not 

 serrated. Dorsulum impressed in the middle; the punctures small 

 distinct, close anteriorly, but separated posteriorly; mesopleura ru- 

 gosely punctured. Scutellum punctured, at the sides depressed 

 Metanotum granular in the middle, smooth laterally, not ridged or 

 channeled; metapleuras granular, posterior face with a fovea above, 



TRANS. AM. ENT. SOC, XXXV. (14) MARCH> 190 g 



