HYMENOPTERA. 431 



6. MiMESA MELLIPES. 



Psen? mellipes. Say, Bost. Journ. i. 369. 1. 

 Hab. N. America (Indiana). 



7. MiMESA BOREALIS. B.M. 



Male. Length 2| lines. — Black : the head shining and finely 

 punctured on the vertex, the face with a thin silvery pubescence ; 

 the antenn<e clavate ; tips of the mandibles ferruginous. Thorax 

 shining and punctured, sparingly pubescent above, more thickly 

 so on the sides and beneath, the pubescence of a silvery bright- 

 ness ; the metathorax very coarsely rugose ; the tarsi pale rufo- 

 testaceous; the wings hyaline and iridescent. Abdomen very 

 smooth and shining, beyond the first segment thinly covered 

 with short silky pubescence; the petiole with a longitudinal 

 central carina, its apex acuminate, and having a central channel 

 running from the base to the apex. 



Hab. Hudson's Bay. 



This species closely resembles the M. unicolor, but the antennae 

 are much more clavate ; the metathorax is also much more coarsely 

 sculptured . 



8. MiMESA ANTENNATA. B.M. 



Female. Length 4| lines. — Black : the head smooth and 

 shghtly shining ; the face and mandibles densely covered with 

 silvery jmbescence ; the clypeus produced, with an obtuse tooth 

 in the middle ; the mandibles ferruginous at their apex ; the 

 antennae longer than the thorax ; the flagellum very slender at 

 the base and much thickened at the apex ; the cheeks armed 

 with stout curved spines. Thorax smooth and shining; the 

 metathorax rounded behind, with a central impressed line in the 

 middle which runs upwards to the verge of the truncation ; 

 wings hyaline, slightly clouded at their apex; the pectus and 

 femora beneath covered with glittering silvery pubescence. 

 Abdomen : the petiole narrowed towards the base ; the abdomen 

 very smooth and shining; the apical segment margined at the sides, 

 and covered with scattered punctures and short glittering hairs. 



The male closely resembles the female, but has the antenna- 

 less thickened at the apex. 



Hab. Sandwich Islands. 



Genus 10. DIODONTUS. 



Crabro, pt., Fabr. Ent. Syst. ii. 293 (1793). 

 Pemphredon, ])t., Fabr. Syst. Piez. 314 (1804). 



