304 HYMENOPTERA ACULEATA. 



(18) 1. Second joint of labial palpi consider- 

 ably more than half the length of 

 the first, generally exceeding the first 

 in length. 



(6) 2. Wings with three submarginal cells. 

 (4) 3. Maxillary palpi six jointed, abdomen 



blue or metallic .... Ceratina. 

 (3) 4. Maxillary palpi one jointed, abdomen 



black with white pubescent spots . Bpeolus. 

 (2) 5. Wings with two submarginal cells. 



(7) 6. One joint only at the apes of the 



labial palpi cylindrical and divergent Chelostoma. 



(6) 7. Two joints at the apex of the labial 

 palpi cylindrical and divergent. 



(9) 8. Species very small, dull, first segment 

 of the abdomen strongly and trans- 

 versely carinated at the base . . Hekiades. 



(8) 9. Abdomen not carinated at the base, 

 or species not very small and dull. 



Maxillary palpi two or three jointed. 



Eyes hairy Ccelioxys. 



Eyes not hairy. 



Apex of the abdomen in the cj spinose, 



denticulate or emarginate, $ with a 



ventral scopa. 

 Abdomen without yellow markings . Megachile. 

 Abdomen with yellow markings . . Antuidium. 

 Apex of the abdomen in the ^ simple, 



$ without a ventral scopa . Stelis. 



Maxillary palpi four jointed . . Osmia. 

 Second joint of labial palpi not, or only 



just half so long as first. 

 Anterior wings with two submarginal 



cells EUCERA. 



Anterior wings with three submarginal 



cells. 

 Maxillary palpi five or six jointed. 



„ „ five jointed . . Melecta. 



„ „ sis jointed . . ANinoPHOEA. 



„ ,, one, two, or four 



jointed. 

 Maxillary palpi four jointed . . Saropoda. 

 „ „ one or two jointed. 



„ ,, two jointed. 



($ , posterior tibia; fringed on their 

 outer margin with short hairs, pos- 

 terior tibiae of $ convex and hairy. Psitutrus. 

 (28) 29. (?, posterior tibia> fringed on their 

 outer margin with long hairs, pos- 

 terior tibiiB of ? concave and 



shining Bombus. 



(27) 30. Maxillary palpi one jointed. . . Apis. 



