AMERICAN HYMENOPTERA. 123 



Diplopleetron cressoni n. sp. 



Female. — Length 5 mm. Clypeus rounded on the anterior margin, 

 without teeth. Head very finely closely punctured, with some large 

 punctures intermixed; a faint line from the lower ocellus' to the 

 clypeus; vertex with, the large punctures denser than on the front; 

 a linear fovea behind each lateral ocellus; distance between the eyes 

 at the top less than the length of antennal joints 3-4, but greater 

 than the length of joints 2-3; ocelli in a rather acute triangle. An- 

 tennal joints three and four equal; basal joints covered with some 

 bristle-like hair. Dorsulum, scutellum and mesopleurae shining with 

 a few punctures. Metanotum finely granular; metapleurse with fine 

 oblique striae; entire metathorax subopaque. Anterior tarsi with a 

 feeble comb; tibiae and tarsi sparsely clothed with bristle-like hairs. 

 Abdomen shining, very minutely punctured. Color uniformly pale 

 ferruginous; apex of the mandibles, palpi, apical part of the antennae 

 piceous or brownish. Wings yellowish hyaline; venation yellowish. 



Habitat.— Boulder, Colorado, June 1, 1908 (S. A. Rohwer). 



This species is most closely related to D. ferrugineus Ashm., 

 but there is no smoky spot in the wings, and there are no 

 black markings. Dedicated to Mr. E. T. Cresson. 



Diploplectron relativus n. sp. 



Female. — -Length 5 mm. Anterior margin of the clypeus in the 

 middle produced into two sharp teeth, which are more widely separated 

 than usual. The antennae except the four basal joints, a spot enclosing 

 the ocelli, pectus, metanotum in part above and the posterior femora 

 at the base black; the rest of the insect ferruginous. Besides the 

 above characters this insect is exactly like D. cressoni, and if the 

 clypeus was not bidentate it could not be separated from it. 



Habitat.— Boulder, Colorado, August 4, 1908 (S. A. Rohwer). 



Mr. H. S. Smith's reference to D . ferrugineous Ashm. (Univ. 

 Nebr. Studies, vii, Oct. 1908, No. 4, p. 15) is perhaps to this 

 species or cressoni, and not ferrugineous. 



The species of Diploplectron may be separated by the 

 following table: 



Anterior margin of the clypeus produced into a bidentate process 1. 



Anterior margin of the clypeus without teeth 6. 



1. Head, thorax and abdomen black 2. 



Head and thorax mostly ferruginous 5. 



2. Costal apical margin of the posterior wings with a smoky spot. ..3. 

 Posterior wings without such a spot 4. 



3. Face black without white markings; anterior wings without a 



cloud; front shining f'ossor Roh. 



TRANS. AM. ENT. SOC, XXXV. MARCH, 1909. 



